The official answer is actually C but i thought it was a trick.Maybe the question is not correct.
We need some clarification on how the GMAT works in situations like this.
Given the information from the question only we can assume fixed costs remain the same and can solve the problem with the information from B.
If they tell us that fixed costs don't remain the same in one of the statements, do we have to count that as information for the problem?
I'd love to hear how you handle stuff like this. The set up here is terrible IMO.