Question

When your body burns calories more efficiently, you

Answer 1

D. increase the amount of muscle mass and decrease the amount of body fat.
I hope this helps:)

Answer 2

I think its D, I say this because when you work out, you burn calories because your body is busy doing something for a long period of time. You gain more muscles in your legs, and don't gain weight because that would be like eating a tub of ice cream in 10 minutes and expecting, that you would loose 10 pounds... No... Hoped I helped you out!