What does the term "digestion" refer to in nutrition?

Digestion refers to the process through which food is broken down into smaller components that the body can use for energy, growth, and cellular repair. This process involves a series of physical and chemical changes that transform food into absorbable nutrients. The correct answer highlights the comprehensive nature of digestion, which encompasses both mechanical processes, such as chewing and the movement of food through the digestive tract, as well as chemical processes, primarily carried out by digestive enzymes and acids that break down complex food molecules into simpler ones.

The other options touch on aspects of nutrition but do not fully encapsulate the definition of digestion. The psychological processes of eating involve behaviors and emotional factors surrounding food choices and consumption, while the absorption of nutrients focuses only on the later stages of digestion where nutrients pass through the intestinal walls into the bloodstream. Finally, the elimination of waste pertains to the digestive process but is distinct from digestion itself, as it involves the expulsion of indigestible materials from the body. Each of these aspects plays a role in nutrition but does not capture the full spectrum of what digestion entails.