All of the following options play a role in determining a person's weight:
- Heredity: Genetics can influence body weight, fat distribution, metabolism, and appetite.
- Activity level: Physical activity and exercise play a significant role in managing weight and overall health.
- Body mass index (BMI): While BMI itself is a measure rather than a determining factor, it can be used to assess whether a person is underweight, normal weight, overweight, or obese, which are related to weight status.
- Body composition: This refers to the ratio of fat to lean mass in the body, and it significantly affects overall weight and health.
So, the answer is all of the above: heredity, activity level, body mass index (BMI), and body composition.