Final answer:
Sociologists use microsociology to analyze social interactions, focusing on small group dynamics and individual interactions, through theories like symbolic interactionism.
Step-by-step explanation:
Sociologists use microsociology to analyze social interactions. This approach is most concerned with studying small groups and individual interactions, contrasting with macrosociology, which examines larger societal trends and structures. Working within the realm of micro-level theories, sociologists employ perspectives such as symbolic interactionism, which focuses on the relationships among individuals within a society and the social constructions shaped through day-to-day interactions. Symbolic interactionists are particularly interested in how people communicate based on a shared understanding of symbols and the patterns of interaction between individuals. Given this information, the correct answer to the question is 'a. microsociology.'