All of the following factors play a role in determining a person's weight:
- Heredity: Genetics can influence body weight and how individuals store fat.
- Activity level: Physical activity affects energy expenditure and can significantly impact weight management.
- Body mass index (BMI): While BMI itself is a measure rather than a direct factor influencing weight, it is often used as an indicator of body weight relative to height.
- Body composition: The proportion of fat, muscle, and other tissues in the body affects overall weight and health.
So, the correct selections are heredity, activity level, body mass index (BMI), and body composition.