Final answer:
In an emergency, people often underestimate the need for action because each person attempts to appear calm.
Step-by-step explanation:
The correct statement among the given options is b. In an emergency, people often underestimate the need for action because each person attempts to appear calm.
The phenomenon described in option b is known as the bystander effect, where individuals are less likely to help or take action in an emergency situation when there are other people present. This is because people tend to assume that someone else will take the responsibility and therefore, they underestimate the need for action.
For example, if a person falls on the ground having a seizure in a crowded place, people may hesitate to help as they may believe that someone else will take care of the situation. This diffusion of responsibility can result in delays in providing assistance.