Which of the following suffixes refers specifically to the act of eating or swallowing?

The suffix that refers specifically to the act of eating or swallowing is -phagia. This term originates from the Greek word "phagein," which means "to eat." In medical terminology, -phagia is commonly used to describe various conditions related to swallowing. For example, "dysphagia" refers to difficulty in swallowing, while "pseudophagia" describes a sensation of swallowing or eating without actually doing so.

The other suffixes have distinct meanings: -phage pertains to an organism that consumes or engulfs, often referring to types of cells or microorganisms that eat or destroy. -pneumonia refers to a condition concerning the lungs, specifically inflammation of lung tissue, and -phobia indicates an irrational fear or aversion to something. These definitions clearly distinguish them from -phagia, reinforcing why it is the appropriate choice for the act of eating or swallowing.