Final answer:
The section of the package insert that explains how the drug works is the Clinical Pharmacology section.
Step-by-step explanation:
The section of the package insert that describes how the drug works is D) Clinical Pharmacology. This section includes important details on the pharmacokinetics and pharmacodynamics of the drug. It provides information about the drug's absorption, distribution, metabolism, and excretion (ADME), alongside how it exerts its effects on the body. Understanding the clinical pharmacology of a drug is essential for determining the correct dosage and administration, as well as for predicting potential side effects and interactions with other medications.