Explanation
Correct answer: C.
Choice C is the best answer because it most logically completes the text’s discussion of why zygomorphic flowers (those with bilateral symmetry) remain open longer than actinomorphic flowers (those with radial symmetry). In this context, “attributed to” means explained as a consequence of. The text indicates that compared with actinomorphic flowers, zygomorphic flowers have a small pool of potential pollinators and that remaining open therefore increases their chances of being pollinated successfully. This would be a reasonable explanation for why zygomorphic flowers remain open on average 1.1 days longer than actinomorphic flowers do. Thus, in context it would be most logical to say that zygomorphic flowers’ extended opening period can likely be attributed to the factors discussed in the text.
Why the other choices are wrong
Choice A
Choice A is incorrect because saying that the extended period in which zygomorphic flowers remain open could be “analogous to,” or comparable to, these flowers’ limited pollinator pool and the fact that remaining open increases their chances of pollination wouldn’t make sense in context. The text presents these factors as a possible explanation for the extended period, not as something that the extended period resembles in some way.
Choice B
Choice B is incorrect because saying that the extended period could be “converted by,” or transformed by, the limited pollinator pool and the increased pollination chances wouldn’t make sense in context. The text presents these factors as a possible cause of the extended period, not as forces that change the period into something else.
Choice D
Choice D is incorrect because in this context, “magnified by” would mean exaggerated by or made more extreme or intense by, neither of which would make sense. The text presents zygomorphic flowers’ limited pollinator pool and the fact that this might require remaining open for longer to increase chances of pollination as factors that could explain why these flowers remain open for extended periods; nothing in the text suggests these are factors that could exaggerate an already-extended period (that is, make the period seem greater or more important than it actually is), or that the extended period is in some way extreme or intense.