They Bystander Effect Is

They bystander effect is:

A) an action by an individual that is intended to benefit another individual or set of individuals.
B) when people feel guilty about something they are not personally responsible for.
C) the underestimation of other people's experience of physical pain as well as the pain of social rejection.
D) a phenomenon is which many people witness a need for help, and the knowledge that there are other witnesses makes it less likely that each particular witness will do anything to help.