The author never makes the claim that mites that reproduce by parthenogenesis can do so at about equal rates. Although it’s true that the two mites the passage identifies reproduce at about equal rates, the author never intends to generalize this fact to other mites that reproduce by parthenogenesis.

Although this sounds like it’s supported by the highlighted line, at least with respect to T-mites, the purpose of the highlighted line isn’t to make this point. The purpose is to show that T-mite populations can increase as rapidly as C-mite populations. Also, (B) isn’t actually supported because the author never generalizes from T-mites to other kinds of predatory mites.

This is something the author states after the highlighted lines, but the highlighted lines support a different point. We know the highlighted line doesn’t support (C), because in the line immediately after the highlighted line, the author says synchrony “also” contributes to predatory efficiency. The “also” means we’re about to get a different feature that contributes to predatory efficiency. The highlighted line, then, is part of a description of the first feature that contributes to predatory efficiency.

Actually, T-mites do not reproduce when C-mites aren’t present. So the egg-laying rate of T-mites is faster in the presence of C-mites.