PT 47 S2 Q20

Until recently, biologists were unable to explain the fact that pathogens—disease-causing ... ...

According to the passage, the prevailing view of the host-parasite relationship is that, in general,
(A) the host is ultimately harmed enough to prevent the parasite from thriving
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: Science & Technology Mix 1