Final Answer:
AZT can become less effective through both scenarios: 1) A person's own cellular physiology changing and 2) Virions mutating inside a person, making them resistant to AZT. Option 3 is answer.
Step-by-step explanation:
A person's own cellular physiology can change: Over time, an individual's physiology may undergo alterations, potentially affecting the efficacy of AZT. Changes in drug metabolism, cell receptivity, or other factors can impact drug effectiveness.
Virions inside a person can mutate, making them resistant to AZT: Viruses, including HIV targeted by AZT, can mutate. Some mutations confer resistance to antiretroviral drugs like AZT, rendering the medication less effective in inhibiting viral replication.
Both are correct: The statement is true. Changes in the person's physiology and viral mutations are independent yet plausible reasons for a decrease in AZT effectiveness.
Neither is correct: This option is incorrect, as both scenarios are potential factors impacting AZT efficacy.
Option 3 is the answer.