Answer: C) people define themselves by their group affiliations.
Explanation: Social identity can be simply defined as the perception of an individual on who they are based on the membership they belong to.
Social identity theory is a theory about (in group) who we are and (out group) who they are, the in group will always look for issues to use against the out groups, there by tarnishing the image of the out groups and enhancing theirs.
So option (C); people define themselves by their group affiliations best illustrates social identity theory.
Answer: Social constructionist theory.
Explanation:
The social constructionist theory states that any social movement is an interactive, symbolically marked, a product of a negotiation process that requires participants, contestants, and spectators. Research conducted under this perspective will focus on the way problems are framed and named by people, depending on their own framework. Different realities might exist among participants involved in the same activities.