It's an interesting question.
You are correct, but cisco believes or wants you to have each user connected to a switch port
so because VLANs don't decrease the number of the users
, there is no reason for decreasing number of switch-ports and so number of switches. If look at the question from this point of view.
I did my CCNA last year, after i finnished the official course and i can tell you, that there are some of "these questions" in this exam.
So you can just shoot in the dark
or try to think in the "cisco-way"