I understand why D is correct, but I'm having trouble understanding why C is incorrect.
C states that the cost of the passes has remained the same, while hotel and meal prices have risen. Maybe I'm mistaken, but in and of itself, that fact alone doesn't seem undermine the hypothesis. My thinking was that, depending on the elasticity of the hotel and restaurant demand curves we can't say for sure what effect this would have on their revenues, and thus I figured it had no effect on the argument. Raising prices might result in increased revenue, or it might result in decreased revenue. We know in the problem that revenue rose, but do we automatically attribute this increased revenue to the price rise? I know I'm overthinking it, but this problem really annoyed me.
Also, long time lurker, and I just wanted to say thanks for all of the awesome information posted in these forums!