​Exercising with a friend or family member can help increase the amount of time you spend on physical activity, and thus________ has been shown to increase a person's likelihood of staying physically active.

A) ​social support
B) ​self-esteem
C) ​depression
D) ​personal trainers

Social support refers to the encouragement, assistance, and companionship provided by others; it has been shown to increase a person's likelihood of staying physically active. Exercising with friends or family members provides social support and can motivate individuals to continue with their physical activity routine. The other options (B, C, and D) are not directly related to the role of social support in physical activity.