Which factor is most likely to influence the likelihood of developing a substance use disorder?

Peer pressure is a significant factor influencing the likelihood of developing a substance use disorder because it directly affects an individual's choices and behaviors in social contexts. Social influences, especially during adolescence and young adulthood, can strongly dictate an individual's inclination to experiment with or use substances. Friends and peers can create an environment where substance use is normalized, increase accessibility to drugs or alcohol, and impose direct or indirect pressure to conform to group behaviors. This social dynamic can significantly impact a person's decisions regarding substance use, making them more susceptible to developing a disorder.

While other factors like regular exercise and completing a college degree can contribute positively to overall well-being and potentially reduce the risk of substance misuse, they do not exert the same immediate social influence as peer pressure. Similarly, living in a rural area may alter the context in which substance use occurs, but it does not have the direct, pervasive influence of peer relationships on an individual’s choices related to drug or alcohol use.