Question

Though neighbors heard someone screaming for help as she was being murdered, they failed to call the police in time to save her. this best illustrates:

Answer 1

The correct answer is the bystander effect.
In psychology, the bystander effect refers to a form of apathy, to the fact that people are less likely to offer someone help if there are other people around. They will think that they don't need to do anything about the situation because someone else will do it. So in the case above, the neighbors might have thought that someone else will call the police, but apparently no one did.