Genetic factors and racial differences are related to biological variability.

• A. False
• B. Not mentioned
• C. Not specified
• D. True

Answer: (D)

Genetic makeup and ancestry influence how a person responds to drugs, causing biological variability. Variants in drug‑metabolizing enzymes, transporters, and targets change pharmacokinetics and pharmacodynamics, so people metabolize and respond to meds differently. Differences in allele frequencies across populations mean racial groups can show different drug responses or risks of adverse effects. For example, CYP2D6 variants affect how some drugs are activated or inactivated, and certain HLA or VKORC1/CYP2C9 variants can alter drug sensitivity or dosing needs. These patterns illustrate that genetic factors—and, by extension, racial differences tied to ancestry—are linked to variability in drug response. Therefore, the statement is true.