Exercising the muscles changes the ratio of and speeds up weight loss.
a. fat to muscle fiber
b. protein to muscle fibers
c. blood to muscle groups
d. oxygen to muscle groups

Explanation:

Thanks to exercises the ratio between fat and muscle fiber is decrease. This happens because fat is actually stored energy, when you eat more than your body needs, this energy deposits begin to grow, making you to gain wait. Another important fact is that fat is denser that muscle fiber, which means that you will weigh a lot more having more fat that more fiber.

In this order, to be able to exercise you need energy which has different source, but at some point, you will need an excess of energy to be able to endurance the exercise, there is when fat is going to be burned. On the other hand, when you stress a muscle with a lot of exercise, its fibers will break, having a crisis, but after the recovery you will gain muscle to prevent a future crisis. So, this dynamic is what make change your ratio fat/muscle.

i think the correct answer is b) humans who reduce their calorie intake by at least 25 percent on a long-term basis will live longer than they would have they not done so. i hope i you out