Does sulfur have various allotropes at room temperature?
"Exists" is an awfully tricky word: it can be understood in a thermodynamic sense or in a kinetic (=everyday) sense, and the meanings are sometimes quite different. Ditto for "stable".

Thermodynamically, there exists only one stable allotrope of any element at any given conditions. All other allotropes are not allowed to exist and must eventually transform to that one. This is true, but the problem is that the transformation may take forever.

Now, your book on sulfur was using this meaning, but your test was not. It was meant to be understood in a kinetic sense, where multiple allotropes may coexist all right. In particular, the high-temperature monoclinic sulfur can be cooled down to room temperature and still remain monoclinic. I can attest to that; I used to hold it with my own hands, as did numerous other chemists. That's what people call metastability.

There is also plastic sulfur and other forms, but that's another story. And as you already know, there is oxygen vs ozone, and white phosphorus vs red, so hydrogen is really the only element here that does not have multiple allotropes.

So it goes.