PT 47 S2 Q19

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

Which one of the following most accurately summarizes the main idea of the passage?
(A) A new hypothesis about the host-incapacitating behavior of some pathogens suggests that directly transmitted pathogens are just as virulent as vector-borne pathogens, due to the former's ability to survive outside a host for long periods of time.
(B) ...
(C) ...
(D) ...
(E) ...

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