I know it may not seem this way, but the fact that you're consistently narrowing it down to 2 answers (including the correct one) is a great sign! It means that you're understanding the argument and the question, and you're eliminating the more obviously wrong answers.

Ask yourself this - when you had it narrowed down to those 2 answer choices, were you asking yourself "which one of these seems right?" or "which one of these can I prove wrong?" It may seem like a minor distinction, but it's actually a very powerful shift in perspective. When you're trying to find the right answer, you'll try to talk yourself into things, and you'll overlook flaws (like words that are too extreme, or a subtle shift in degree from the argument). If you're trying to prove things wrong, though, you'll pick up on all of those little flaws.

When the test writers are writing these questions, they want to come up with wrong answer choices that will be tempting. The easiest way to do that is to take an answer that's almost right, but subtly tweak a word or two until it's not longer completely provable. If you pick those answers, you're falling into their trap! Focusing on the wrong answers rather than the right ones will help you to avoid these traps.