The nutrients which serve as the main sources of energy for the body are
a. proteins.
b. fats.
c. carbohydrates.
d. vitamins.

The answer is definitely carbohydrates. A lot do claim that this serves as the fuel that we need in our everyday lives which is why we must take carbohydrate-rich food such as bread and rice. Therefore, the answer is C.

Animals will lose energy because it is converted to heat