Malaria is caused by several different species of
Plasmodium, a protozoan parasite. Plasmodium resistance to the common drugs used to treat malaria has increased in recent years In a scientific study.Plasmodium samples were analyzed in blood drawn from a large number of infected patients before drug treatment and
subsequently from the subset of infected patients with drug-resistant Plasmodium. DNA sequences of four different Plasmodtum genes thought to be involved in resistance were compared between samples from patients with drug-sensitive Plasmodium and patients with drug-resistant Plasmodium.
Which of the following best supports the hypothesis that preexisting mutations confer drug resistance?
(A) Drug resistance can sometimes be reversed
by simultaneous treatment with a drug that inhibits the drug-pumping mechanism of Plasmodium. (B) Some of the mutations that occur most frequently in samples from patients treated with antimalarial drugs are detectable in Plasmodium samples collected prior to use of antimalarial drugs
(C) Continued use of the same antimalarial drugs leads to increased Plasmodium resistance.
(D) The same mechanism of drug resistance in Plasmodia isolated from separate
populations of patients resulted from an accumulation of new genetic mutations