To be effective, exercise must reach at least of your maximum ability.
a) 80%
b) 40%
c) 60%

I would say 90% of your maximum ability, because I am athletic.

But in most scenarios, it should be c) 60%

hope this helps!! :D

the maintenance of fluid balance during exercise. author information: fluid supplementation is necessary for exercise in which fluid losses must be offset by intake to avoid the negative effects of hypohydration on health and performance.