Hey All,
I'm happy to weigh in on this one, though it's definitely tricky. First of all, who put this in a category called "Verb Tense"? The splits here are idiomatic (between/among) and pronoun based (its/their). There aren't even any verbs in the answer choices!

Either way, "its" and "their" are both possessive pronouns, so we have to ask ourselves exactly WHAT is being possessed. In this case, what has "potential uses". Is it science? No, because the science could be applied both pragmatically and merely "for the discovery of new truths". Is it "discovery"? No, because you can't use a discovery to do anything. It has to be "new truths". Why? Remember that "discovery" does not stand alone. Imagine for a moment that they had used the word "techniques" instead of "truths". Now, there'd be no question in your mind. "Techniques" can be used, but "the discovery of new techniques" cannot. The same applies here. "Truths" can have uses far more logically than "the discovery of new truths" can.
This means we need "their", and we obviously need "among" (for three or more choices, not just two), so the answer is E.
Hope that helps!
Tommy Wallach
Whereas pure science is mainly concerned with the discovery of new truths and makes few, if any, attempts to discern the best options between their potential uses, applied science involves the application of existing truths to concrete problems.
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