Final answer:
Charles H. Cooley is the sociologist who distinguished between primary and secondary groups, with family as an example of a primary group and a classroom as a secondary group.
This correct answer is A.
Step-by-step explanation:
The sociologist who first defined the differences between primary and secondary groups i
Cooley, in his work, differentiated between these two distinctive types of groups. Primary groups, as described by Cooley, are smaller and involve long-term, face-to-face, emotional interactions, serving expressive functions, with the family being a prime example.
On the other hand, secondary groups are larger, more impersonal, often task-focused, and serve instrumental functions, like a classroom or an office environment.
This correct answer is A.