It’s not a good test question in my opinion, because it’s not very clear what “superior need” (I have never heard of “superior need” before) means. I suppose you can meaningfully talk about “manifesting a need”, but I’m not sure what it means to manifest a “superior need”. “Superior need” here means - as I understand it - that man believes his needs are more important than the needs of the whales (so he feels entitled to kill them). So I think “assumes” is the only word that makes sense in the context.

Thanks for the responds! The explanation to the question says that "assume" in the context means "suppose something to be true". The reason why I chose E is that I thought to manifest a quality means to show/display a quality. We can show/display a need with our expressions or actions, and I think that makes sense. BTW this a question from a GRE mock test, therefore it maybe a little bit controversial and I am still confused.

This is a worthless question most likely written by a non-native speaker. It has no value.

Hmmm, these are indeed large words. 'Assume' - #1 to believe a piece of information without proof. #2 to 'take on' a responsibility. 'Manifest' - to create/to grow/to make by taking action. Assume fits better because we, as humans, 'take on' a superior need than a whale (or other animal). We can't really 'make/manifest' a need by taking action. A need is something that is just part of us. For example: we need food. We need water. We need shelter. But how do we 'make/manifest' the desire to want food or water? This is an extreme example, I think, however - I think it will help prove the point a bit more. I hope this helps a little?! [emoji]

挺难，我怎么觉得该用 assume 而不是 assumes 呢