Within a Few Weeks of Treatment with the Drug 3TC

Multiple Choice

Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained?

A) HIV can change its surface proteins and resist vaccines.
B) The patient must have become reinfected with 3TC-resistant viruses.
C) HIV began making drug-resistant versions of reverse transcriptase in response to the drug.
D) A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency.
E) The drug caused the HIV RNA to change.