In the bystander effect, the correct answer is:
a) People fail to act because they assume other people will take action.
This phenomenon occurs when individuals in a group do not offer help to a person in need because they believe someone else will intervene. The diffusion of responsibility among group members leads to inaction, assuming others will take charge. This effect highlights the impact of group dynamics on individual behavior in situations requiring assistance or intervention. It is essential to recognize this effect to understand how group influence can influence individual decisions in social contexts.