What defines physiological dependence on a substance?

Physiological dependence on a substance is primarily characterized by the presence of tolerance and withdrawal symptoms. Tolerance refers to the body's adaptation to the substance, requiring the individual to consume larger amounts to achieve the same effect. Withdrawal symptoms occur when the substance is reduced or discontinued, signaling the body’s physical dependence on it.

This understanding highlights that simply feeling cravings for a substance does not indicate physiological dependence; rather, it is the physical effects on the body, such as tolerance and withdrawal, that define this condition. Continuous use without withdrawal symptoms, while indicative of regular consumption, does not necessarily confirm physiological dependence either, as an individual may be using a substance without experiencing the body's adaptive changes that define dependence. Thus, the correct answer encompasses the crucial aspects of both tolerance and withdrawal, which are fundamental to understanding physiological dependence.