Which of the following involves the physical grinding and chewing of food?

The correct choice pertains to the role of teeth in the digestive process. Teeth are specifically designed for mechanical processing of food, which includes actions like grinding and chewing. This process, known as mastication, is crucial for breaking down food into smaller, more manageable pieces that can be easily swallowed and subsequently digested.

Salivation mainly refers to the production and secretion of saliva, which helps moisten food but does not involve the physical breakdown of food itself. Peristalsis is a type of muscular contraction that moves food through the digestive tract rather than grinding or chewing it. Digestion encompasses the overall process of breaking down food, including both mechanical and chemical processes, but the specific action of grinding and chewing is distinctly attributed to teeth. Thus, understanding the role of each component in the digestive process highlights why teeth are the correct answer here.