This question is asking us that the scientists mentioned in line 10 think about the prevailing view of parasite-host relations. We should recap what the scientists think and what the prevailing view is.
We see the prevailing view around line 6, which is that hosts and parasites eventually develop a benign coexistence.
The scientists mentioned in line 10 reject this view, and think that a pathogen that kills its host could still have evolutionary success.
(A) is unsupported. We do not know if the biologists think that most relationships are not benign, only some. (B) Is the opposite of the prevailing view. (C) Is unsupported. The scientists are not disputing that they can be benign, rather, they dispute the idea that they are always benign. (D) Is exactly what we saw. The scientists (in line 14) note that there is another path to evolutionary success beyond what the prevailing view says. (E) Is not even close to anything in the passage.