Michael has gained 10 pounds since he became close friends with matt, who is 75 pounds overweight. michael finds that he eats larger portions and more unhealthy foods when he is around matt. michael's change in diet and weight gain can be explained by the impact of

The correct answer is social influence. 

Social influence refers to the phenomenon where a person's thoughts, beliefs, behaviors and actions are influenced or affected by those around them. Social influence can manifest in three forms: conformity, compliance and obedience. In Michael's case by eating larger portions and more unhealthy foods when he is around Matt, the conformity aspect of social influence is coming into play.