Which of the Following Is Direct Evidence for the Social

Which of the following is direct evidence for the social brain hypothesis?

A) Humans outperform other primates in physical problem-solving tasks.
B) Species of whales and birds that are more social have smaller brains.
C) Humans have a large encephalization quotient.
D) Animals that are more social have fewer cognitive skills.
E) As predicted by the neocortex ratio, the average human social group size in subsistence societies is around 150 members.