Final answer:
Charles Horton Cooley focused his sociological studies on groups of friends and families, emphasizing the impact of primary groups, such as families, on individual socialization and identity formation.
Step-by-step explanation:
Charles Horton Cooley pursued the discipline of sociology by primarily focusing on the study of groups of friends and families. Cooley is well-known for his concept of the 'looking-glass self', which posits that individuals shape their self-concepts based on their understanding of how others perceive them. This concept underscores the importance of social interactions in forming identity.
Cooley also identified and differentiated between two types of groups: primary groups and secondary groups. The primary group serves emotional needs and is exemplified by the family, which plays a critical role in our lives, serving expressive functions. Secondary groups, which can include a classroom or office, are larger, more impersonal, and typically serve an instrumental, task-oriented function.
While Cooley wrote extensively on social organization and group dynamics, he did not directly focus his work on the study of governments or corporations. Therefore, the correct answers to the question are options A (Groups of friends) and B (Families).