Who will be more physically active at age (3-5) or (6-7) or (18-65)? Who will be less physically active? Why?

younger people will be more physically active than older people

Explanation:

when you're young, you have a lot of energy and you're still growing. older people don't have the capability to do as much physical activity as a young person does, so they are less physically active. the exercise capability of people decreases with age, as people's bodies age and become weaker with time.