Our family and very close friends are a significant part of our lives as social beings. What term did Charles Horton Cooley introduce to describe this important aspect of our lives?

Primary group.

Explanation:

Charles Horton Cooley wanted to have a better understanding of the society and human behavior. He wanted to know the influence of some groups within a society and its impact on the behavior of humans. His major contribution was about primary groups. Cooley described primary group as the first group one gets introduced to and has the most effect on an individual's beliefs, ideas and ideals. Our families and very close friends are part of the primary groups Cooley wrote about. They are essential part of our lives. Even though there has been several evolvement, family and friends play an active role in our behavior and belief.

the answer is d.index