True : Mary is using a garbage can model of decision making. 
The garbage can model is an irrational model of decision-making, which assumes that problems, solutions and participants are disconnected and exist as separate organizational streams. Choice opportunities are initiated by the organization, but none or few problems may be solved in the process and then only by chance.
The garbage can model also known as garbage can process, or garbage can theory describes the chaotic reality of organizational decision making in an organized anarchy. The model originated in the 1972 seminal paper, A Garbage Can Model of Organizational Choice, written by Michael D. Cohen, James G. March, and Johan P. Olsen.
Organized anarchies are organizations, or decision situations also known as choice opportunities, characterized by problematic preferences, unclear technology, and fluid participation. While some organizations such as public, educational, and illegitimate organizations are more frequently characterized by these traits of organized anarchy, the traits can be partially descriptive of any organization, part of the time.

Explanation:

True : Mary is using a garbage can model of decision making. 
The garbage can model is an irrational model of decision-making, which assumes that problems, solutions and participants are disconnected and exist as separate organizational streams. Choice opportunities are initiated by the organization, but none or few problems may be solved in the process and then only by chance.
The garbage can model also known as garbage can process, or garbage can theory describes the chaotic reality of organizational decision making in an organized anarchy. The model originated in the 1972 seminal paper, A Garbage Can Model of Organizational Choice, written by Michael D. Cohen, James G. March, and Johan P. Olsen.
Organized anarchies are organizations, or decision situations also known as choice opportunities, characterized by problematic preferences, unclear technology, and fluid participation .While some organizations such as public, educational, and illegitimate organizations are more frequently characterized by these traits of organized anarchy, the traits can be partially descriptive of any organization, part of the time.
Within this context, of an organized anarchy view of organizational decision making, the garbage can model symbolizes the choice-opportunity/decision-situation for example: a meeting where ideas are discussed and decided on as a "garbage can" that participants are chaotically dumping problems and solutions into, as they are being generated. The "garbage can" term's significance is best understood by considering the manner in which items in a trash can are organized, which is a messy, chaotic mix. The model portrays problems, solutions, and participants/decision-makers as three independent "streams" that are each generated separately, and flow disconnected from each other. These three streams only meet when the fourth stream of choice opportunity arises, as a garbage can, for the streams to flow into. The mix of garbage streams in a single can( choice opportunity) depends on the mix of cans available, on the labels attached to each can, and on what garbage is currently being generated. The mix of garbage in a single can also depend on the speed at which the garbage is collected and removed from the scene, for example, how long before problems, solutions, and/or participants move on to other choice opportunities, or, depending on how long the current choice opportunity remains available. This anarchic view of decision making contrasts with traditional decision theory.

The Garbage Can Mode as explained by Cohen and Olsen.
In Cohen, March and Olsen's view, decision makers often operate in an irrational environment with a lot of uncertainty. As a result, they make decisions without following the rational approach of gathering facts and weighing the evidence thoughtfully. Garbage can decision making doesn't go looking for the perfect solution. Instead, it mixes and matches the elements the organization has already piled into the can:

Choices looking for problems
Issues and feelings looking for decisions to affect
Solutions looking for issues they can resolve
Decision-makers looking for something to do
The original 1972 theory concentrated on academic institutions. Later writers expanded it to decision making in business. For a garbage can theory example, consider an entrepreneur who is launching his third or fourth startup. When he runs into a problem, his first thought might be to draw on experience: reach into the garbage can for one of the solutions he's used in similar situations before.

Is the Model True..
The creators of the garbage can model weren't recommending this approach as a way to make decisions. Instead, they claimed this was how decision making usually worked. Problem solving in this model is an anarchic mess where managers simply seize the first solution they dredge out of the trash. Because that solution worked once, it might fix things again, but that isn't a slam dunk.
Critics of the model have several objections. One is that we don't pick solutions completely randomly, even when we're under pressure. Instead, we're restrained by our pre-existing biases. Another objection is that while many decisions may look random, that's because we can't see some of the underlying influences shaping them.
There hasn't been a lot of research to confirm or disprove the original garbage can model. This may be because people want leaders to make informed, well thought out and rational decisions. Irrational decision making is seen as something to avoid, not study and analyze.

Does it Solve Anything...
The garbage can approach sounds like it would produce garbage results. That's not necessarily true. A successful entrepreneur or manager often has plenty of experience solving business problems. Drawing on that past experience by reaching into the can can produce a good solution for current problems.
Using what's in the garbage can guarantees you won't come up with anything new or original that you haven't tried before. That can be a mistake. If the best solution to the current problem is a new idea, restricting yourself to what's in the can won't get you the best results. Entrepreneurs who come up with new ideas can add them to the can for future problem-solving efforts.
Cohen, March and Olsen believed garbage can decision making would produce suboptimal results. The manager's choice might solve the problem eventually, but another choice might have resolved things just as well. Other problems just bounce from solution to solution without really getting resolved. The trio list several possible outcomes from garbage can decision making:
Flight. Problems wait in the can for a long while without being matched up with a usable solution. In the end, they're never solved.
Oversight. The decision makers are desperate to solve a problem, so they grab a solution from the can and apply it. The solution doesn't really fit, but the deciders can claim everything's been resolved.
Resolution. Sometimes, management will dredge up solutions from the garbage can that actually solve the problem. This is more due to luck and chance than any sort of rational process.

Why Decide garbage can
The creators of the garbage can model believed people made decisions this way because rational, formal decision making often wasn't practical.
School principals, for instance, have to reach decisions while navigating among multiple stakeholders: students, teachers, parents, local school boards and other officials and possibly the local community. Trying to balance the desires of all these interested parties with a rational, analytical, calmly reasoned approach often proves impossible. That's particularly true when decisions have to be made within a limited time, often under pressure.

The results?
Principals default to making decisions based on their experience of what works and the community's opinion of what outcomes are acceptable. They also want to make it obvious that they're working hard on the problem. They may make decisions just to demonstrate that the school is working on solutions, even if the solutions aren't helpful.

How Leaders Can Help
In Cohen, March and Olsen's view, leadership has a limited role in shaping the organization's decisions. A good leader can't stop garbage can decision making, but they can influence what comes out of the can:
They set the timetable for when the organization tackles issues or problems.
They're sensitive to the interests and involvement of the staff working on solutions.
They drop problem-solving initiatives that have become hopelessly tangled and ineffective.
They accept that their plans may be more symbolic than productive.
They decide how much effort and energy to devote to solving a problem.
They provide connections to the available resources.
A study of IT project success and failure found that the outcomes depended on whether the leadership was hierarchical and top-down or empowered lower-ranked employees to participate. Projects that allowed for more participation in decisions were more likely to succeed.
Perhaps the most effective thing leaders can do is make a conscious choice not to use garbage can decision making. A deliberate effort to look for new solutions and ideas rather than recycle whatever's in the can or whatever causes the least inconvenience can go a long way toward producing good results.

Reference:
Einsiedel Jr., A. A. (1983)"Decision-making and problem solving skills".
Richard Harrison, ‎Alessandro Lomi,(2012)."Garbage Can Model of Organizational Choice".