Answer:
C. diffusion of responsibility.
Step-by-step explanation:
Diffusion of responsibility: In psychology, the term diffusion of responsibility was given by Bibb Latané and John Darley, and is defined as a socio-psychological phenomenon in which an individual is less likely to carry out responsibility for specific inaction or action if other persons are present at the moment.
Example: An individual is travelling on a busy road and suddenly he encountered that a lady met with an accident but he didn't go for help because of the presence of other people.
In the question above, the students' failure to help is best explained in terms of diffusion of responsibility.