Physiology is best defined as:

Physiology is focused specifically on understanding the functions and processes of the body and its systems. This includes how organs and systems work together to maintain life, respond to stimuli, and perform various metabolic processes. The study encompasses everything from cellular function to organ systems and how they interact to sustain the body’s health and performance.

By choosing the definition that highlights body function, it emphasizes the dynamic processes involved, such as circulation, respiration, and digestion, rather than merely describing structures or physical movements. Thus, it is clear that physiology is distinct in its focus on the functioning aspects of biological systems, differentiating it from studies that look at anatomy, movement, or pathology.