Which theoretical perspective would suggest that group memberships are used to separate and differentially treat individuals on the basis of their categorization?

Conflict theory

Explanation:

Conflict is a natural phenomenon in every society, that is, it is a social fact inherent to life in society. The theory of realistic conflict Sherif and Sherif (1979) defined this field of research as the analysis of those behaviors and attitudes that arise from the concrete or desired belonging to a human group. This line of work then deals with the intergroup behaviors of the subjects, that is, with the similarities and uniformities in the behavioral patterns that emerge from the perception of oneself and others in terms of their ascription to a social group. In this theory the conflict is analyzed from social psychology with a perspective of intergroup relations. It states that the conflict arises from the relationship established by two groups for obtaining resources.