Which is an example of mechanical digestion that occurs in the human digestive system? A. Saliva in the mouth acts to moisten and break apart food molecules.

B. The muscular lining of the esophagus pushes food from the mouth to the stomach.

C. The muscular walls of the stomach act to churn food back and forth.

D. Small molecules, such as glucose, are absorbed into the blood from the small intestine.