Multidrug Treatment of HIV-1 Is Preferred Over Single-Drug Treatment Because

Multidrug treatment of HIV-1 is preferred over single-drug treatment because

A) the high mutation rate of HIV-1 means that many drugs are not likely to work against it.
B) multidrug treatment places a more challenging selective pressure on the virus; to survive requires multiple mutations.
C) protecting itself against one drug makes the virus less able to protect itself against the others.
D) the drugs work synergistically with each other.
E) one drug makes the virus more susceptible to the others.