Questions: Which of the following is an agent of mechanical digestion in the mouth? a.) Saliva b.) Peristalsis c.) Teeth d.) Salivary amylase

The answer is the third one (c): Teeth.

Explanation for each option: a.) Saliva - Incorrect. Saliva is a fluid produced by the salivary glands that helps moisten food and contains enzymes, but it does not mechanically break down food. b.) Peristalsis - Incorrect. Peristalsis refers to the wave-like muscle contractions that move food through the digestive tract, primarily occurring in the esophagus, stomach, and intestines, not in the mouth. c.) Teeth - Correct. Teeth are responsible for the mechanical digestion in the mouth by physically breaking down food into smaller pieces through chewing. d.) Salivary amylase - Incorrect. Salivary amylase is an enzyme found in saliva that begins the chemical digestion of carbohydrates, not mechanical digestion.

Summary: Teeth are the agents of mechanical digestion in the mouth, as they physically break down food into smaller pieces through the process of chewing.