Which theory suggests that drug use is primarily influenced by a person's social relationships?

The theory suggesting that drug use is primarily influenced by a person's social relationships is indeed Social Influence Theory. This theory emphasizes the impact of social networks and peer pressure on an individual's decisions regarding substance use. It posits that a person is more likely to engage in drug use if they have friends or social circles that normalize or encourage such behavior. This can include direct influences, such as friends offering drugs, as well as indirect influences, where societal norms and expectations within a group foster a culture of substance use.

In contrast to this theory, Imitation Theory focuses on the idea that individuals may adopt behaviors by mimicking others without a strong emphasis on social relationships. Structural Influence Theory examines how broader social structures, like socioeconomic status and community norms, affect individual behavior, but it does not isolate the influence of specific social ties. Conditioning Theory, on the other hand, is based on behavioral psychology, explaining substance use through learned responses rather than social interactions.

Thus, Social Influence Theory accurately captures the essence of how interpersonal relationships and social contexts drive drug use behaviors.