Yes, yes, I encourage you to follow Zeke's advice. That sounds like a mistake on the test-maker's part. If you can put forward a decent case for both problems, I bet that you would have a good result.
Oh, wait, am I not supposed to come uninvited?
EDIT: And whoops! Didn't notice new page. How sloppy of me!
Yeah, I plan on bringing it to the teachers attention tomorrow when we get the grades for the test. If noone else mentions it before me, I wouldn't be surprised if multiple students agree with both me and the student I talked to after the test last week. We'll see how it goes.
Update: Turns out I guessed correctly on the question. Nevertheless, I asked the teacher about the question, and what it boils down to is that many phrases and terms in economics have quite different meanings than in ordinary conversation. Reading the question from an every day point of view makes the question seem to have two possible answers. However, from an economist's point of view, it could only be answer "Q" and not "Z." That being said, I do not recall covering the specific words/phrases in that particular problem. It's quite possible I just missed that part of the class though.