Which theory focuses on the interactions and influences within a group?

The correct choice is Systems Theory, which emphasizes the complex interactions and influences within a group. This theory is grounded in the idea that individuals do not exist in isolation; rather, they are part of interconnected systems that affect and are affected by each other. In a family context, for instance, Systems Theory explores how family members interact, how their relationships impact individual behaviors, and how overall family dynamics can shape individual identities and actions.

Systems Theory also highlights the importance of boundaries and feedback loops in maintaining the stability or change within these groups. This approach allows for a comprehensive understanding of how different elements within a group contribute to its functioning and how external pressures can influence it.

While other theories such as Functionalism look at societal structures and their roles, or Social Exchange Theory which focuses on the cost-benefit analysis in social interactions, they do not primarily center on the intricate dynamics and relationships inherent in group interactions as Systems Theory does. Developmental Theory, on the other hand, mainly addresses individual growth and the stages of human development rather than group interactions. Thus, Systems Theory is the most fitting choice for understanding the interactions and influences among group members.