_________ refers to drug craving. a. psychological dependence b. antagonism c. agonism d. physical dependence

First, let's define each term to understand them better:\n\n- Psychological dependence: This occurs when a substance becomes central to a person’s thoughts, emotions, and activities. It usually involves cravings and substance use to relieve withdrawal symptoms or to induce pleasure.\n\n- Antagonism: In pharmacology, this refers to a situation in which a substance acts against and blocks the action of another substance in the body. It does not directly relate to drug craving.\n\n- Agonism: This is when a substance triggers a response in the body after binding to a receptor. However, it's not directly associated with drug cravings.\n\n- Physical dependence: This is a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction. It's not synonymous with drug craving as it's more about physiological response to drug absence.

From the definitions, it's clear that the term that refers to drug craving is psychological dependence. This term encompasses the emotional and mental aspects of substance use, including cravings.