Tricky test makers and their tricks
Particularly with regards to standardized tests, the test makers are not only testing for competency, which could be tested with straightforward questions, but are also testing for excellence, to separate out each test taker by their percentile rank, and to sort among percentiles the difference between Top 20%, Top 10%, Top 5%, Top 1%, and even to smaller units. Thus, test makers often use not only the problem, but they often use a non-standard or non-intuitive presentation of the information and often deliberately pick potential answers that either mislead the test taker or that confirm a common mistake that test takers might make. But this effort is also a test taker's biggest advantage and opportunity. An ambush is not an ambush if the person being ambushed knows about it ahead of time.
Thus, when preparing for and taking standardized tests, the test taker should be on the lookout for non-standard presentations of questions, and be weary of selecting an obvious or easy answer, as signs that the test maker may have set a trap for you. Even under time pressure spending 15-20 seconds analyzing the problem to ensure that you know (1) what the exact question is, (2) how to order the information correctly in order to solve the problem, and (3) to determine if there is a trick that makes the problem easier can be a good way to improve your overall score and separate yourself into a higher percentile result with little additional effort on your part, except to stop and think.