Please read (and follow!) the forum guidelines before posting.
This folder is only for general strategy questions, not content or specific test problems. Check out the problem folders and post in the relevant folder depending upon the source of the problem you want to post (and make sure to follow the rules about banned sources). If you are a course student, you can also ask about other problems or issues before or after class or during office hours.
I'll give you one hint, though. Notice that, in the answers, the units digit is different for every answer choice...
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