When We Metabolize Our Food,we Produce Heat That Helps to Keep

When we metabolize our food,we produce heat that helps to keep us warm.Which of the following best describes why?

A) Chewing is exothermic; therefore, energy is released in the form of heat when we eat food.
B) When we break down food, all energy in the food is directly released in the form of heat.
C) Producing ATP from ADP is exothermic; therefore, energy is released in the form of heat.
D) When we break down our food, the reactions are not 100 percent efficient; therefore, energy is lost as heat.