one nice criterion, which you may not have used previously, is the fact that ASSUMPTIONS must absolutely STAY WITHIN THE STRICT SCOPE OF THE PASSAGE.

this means that any "assumption" answer choice that ventures outside the scope of the passage, or introduces anything irrelevant, is not a required assumption.

this includes "assumptions" that make distinctions that are not made in the passage itself.

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this standard, while not enough to select the correct answer for every problem, makes for some quick eliminations. for instance, in problem #7 in the purple OG verbal supplement (please don't post details here), "normal or high" scores on the immune system test are GROUPED together. therefore, any answer choice that distinguishes "normal" from "high", or separates/isolates one of those two groups, is automatically wrong. (there are 2 such answer choices.) also, on the same problem, the last answer choice is immediately wrong because it mentions "treatment", which is not in any way relevant to the content of the passage.

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when you apply this standard - eliminate anything that's irrelevant or draws nonessential distinctions - you'll find that you should be able to eliminate large #s of incorrect answer choices.