I dont think we can make either of the following assumptions:
(a) edge of the cube in feet is an integer
(b) 6s^2 = 63 => s = 3
If we don't make these assumptions:
6s^2 = 63
=> s^2 = 10.5
=> volume = s^3 = 10.5 ^ (3/2) = 34 sq feet
I agree. I did it the same way.
I have seen lately a number of questions with wrong OAs (not necessarily this one). I would suggest posting next to these kinds of OAs which the poster is not sure about words like 'OA but not sure!'
Many times it happen that the questions are wrongly worded, OAs are incorrect, or both.
This will help us focus on the concept rather than try to fit our concepts to the answer choices.