Answer: diffusion of responsibility
Explanation: Diffusion of responsibility is a phenomenon which occurs when an individual is reluctant to take responsibility simply because he or she feels other are present and should take up the responsibility. It often occurs when the request to take up certain responsibilities is directed to people in a group rather than to a specified person.
In the scenario above, Katcha expects three volunteers will definitely arise either because she taught it is their responsibility to do so, and unless they do not volunteer, then she can take up the responsibility.