Final answer:
The correct answer is c. Reference group. A reference group is a group whose values, norms, and beliefs serve as a standard for one's own behavior.
Step-by-step explanation:
The correct answer to the question is c. Reference group. A reference group is a group whose values, norms, and beliefs serve as a standard for one's own behavior. When individuals alter their group roles to accommodate one person, they are conforming to the expectations and norms of the reference group.