Final answer:
Pedro's tightly knit group of six close friends is considered a clique, which is a small, intimate group that functions as a peer group. Cliques, peer groups, and primary groups influence individuals' behaviors, serving as reference groups.
Step-by-step explanation:
Pedro belongs to a tightly knit peer group that consists of six close friends. In sociological terms, this type of intimate and close-knit group would typically be referred to as a clique. A clique is a small group of friends who interact frequently and share a strong sense of affinity and identity. This is different from a crowd, which is usually larger and less intimate; a gang, which is often associated with illicit or exclusive activities; and an affiliation which is more about formal membership.
Peer groups play a significant role in the socialization process, particularly during adolescence. They have their own norms and often serve as a reference group influencing behavior and outlooks on life.
Finally, primary groups are characterized by close relationships and long-term interactions, and indeed a clique often fits this description as it involves complex, deep relationships unlike the more impersonal affiliations of a secondary group or formal organization.