Thanks to Mike from PWN the SAT for pointing this out to me after my post about why prep books aren’t enough if you want to kick butt on Reading. While it does come in handy to have a context for what you’re reading, a little knowledge can be a dangerous thing. Even if you’ve heard this before, you can stand to hear it again: when it comes to Reading, the correct answer can always be determined based on the information in the passage and the passage alone.
Do not ever pick an answer unless it is directly supported by the passage itself; it doesn’t matter how much it appeals to you otherwise. If it’s not in the passage, it’s wrong, end of story.
That said, I’m also going to suggest something mildly heretical in the land of test-prep: if you do have prior knowledge of a topic and an answer happens to fit both with that knowledge and with the general point of the passage itself (that second one is really key), I’d suggest you check that answer first. In my experience, it often will be correct. The SAT and the ACT reward smart guessing, and making a logical conjecture often pays off. But I emphasize that this is just a strategy for potentially getting to the correct answer faster. You should never pick an answer based strictly on your knowledge of a subject.
The only time I would ever even maybe suggest you try this without going back to the passage would be if you had five seconds left to finish the section, thought the answer could work based on your knowledge of the passage, and felt like taking a walk on the wild side (relatively speaking). But even then, you might want to play it safe.