joseph.m.kirby Wrote:The problems with (D) include:
-The absence of viruses "can" facilitate (perhaps in this case it doesn't)
-If the absence of viruses, in this case, did facilitate the flourishing of bacteria (assumption 1), and these bacteria sometimes damage organisms (in this case, let's assume that they did "damage" the plankton, assumption 2), then we would also have to assume (assumption 3) that the damage would cause a reduction in the population. However, perhaps the damage just relates to a deformity that doesn't necessarily affect plankton bumping-and-grinding. Overall, (D) requires a lot of assumptions, which makes this answer not as attractive as (C).
It's the full combination of factors that makes C better. All of the terms and phrases sound weak in the statement "can facilitate the flourishing of bacteria that sometimes damage other organisms." It "can facilitate the flourishing", flourishing that only (sometimes) damages other organisms? That sounds vague and weak, compared to "Plankton utilize the nutrients released by the death of organisms killed by viruses," which is specific, and happens consistently.