The energy to perform actions, as well as the materials from which body cells and tissues are made, comes from

a. cellulose.

c. food.

b. oxygen.

d. blood.

The function of the digestive system is to food into smaller compounds. The breaking down of food starts from the mouth. The purpose is it is much easier for the food to enter into the esophagus (connected from the mouth to the stomach). Then it enters into the stomach where digestive enzymes break down the food into smaller molecules. This is the most important part since the smaller molecules can enter into the smaller parts in the body need for nutrition. This nutrition gives energy for the body to perform actions. The answer is letter C.