Answer:
When there is a great amount of people and someone who requires help the phenomenom that happens when they don't help hims is called: bystander apathy.
Step-by-step explanation:
To understand this answer we need to analyze it, even though you don't provide the answer choices I can identify it pretty well because it provides all the elements of Bystander apathy. First of all bystander apathy is a concept inside the social psychology discipline that explains why people won't help someone if they see there is a big group of people present in the scene. Because they have the assumption that someone is going to help them. However, at the end of the day, it is apathy.