What defines the act of consuming food or liquids?

Ingestion is the term that specifically refers to the process of taking in food or liquids through the mouth. This process is essential for nutrition, as it is how organisms acquire the necessary substances for energy, growth, and maintenance of bodily functions. During ingestion, food or liquids undergo mechanical and chemical processes as they are broken down into smaller particles that can be absorbed and utilized by the body.

The other options describe different physiological processes. Excretion relates to the elimination of waste materials from the body, while inhalation refers to the act of taking air into the lungs for respiration. Infusion, on the other hand, generally refers to the introduction of a liquid, often for medical purposes, directly into the body but does not relate to the natural act of consuming food or drink. Thus, ingestion is the appropriate term for the act of consuming food or liquids.