Final answer:
A characteristic of a primary group, according to Charles Cooley, is intimate, face-to-face interactions (Option D). Primary groups are marked by close, personal relationships and emotional bonds.
Step-by-step explanation:
According to Charles Cooley, a characteristic of a primary group is D. Intimate, face-to-face interactions. Primary groups are small, consisting of individuals who engage in long-term, emotional and face-to-face relationships that serve emotional needs. Examples include a family or close-knit friend groups, where there's a strong sense of connection and shared life experiences. In contrast, secondary groups are typically larger, more impersonal, and task-oriented, such as a workplace or classroom, where the connections among members tend to focus on achieving specific goals.