Explanation

Creating a filter: on our way through the prompt, we snag on the pronoun "they" and must ask whether it has a clear reference. It seems to refer to the one plural word, "terms." However, at the beginning of the sentence, the phase "there are terms" uses the suspicious construction "there are." It's unnecessary and distorting, because the effect of the terms isn't due to their mere existence, but rather due to what they specifically stipulate. On those grounds, (A) is out.

Applying the filter: choice (B) removes the problem in (A) with "there are" and may be accurate, so we can come back to it. Choice (C) distorts the intended meaning, because it communicates that the vessel is "partly deterring." Choice (C) is out. In (D), the pronoun "this" is being used to refer to an entire clause, which is considered imprecise in English. Choice (E) uses "which" -- does it have a clear reference? It could refer to "terms" sensibly, but then it would have to be plural, so (E) is out. We are left with one choice. The correct answer is (B).