The language of the question is all over the place and a bit of a mess however it actually makes sense ( can't say if it is a gmat like question but a good one nonetheless)
Question simplified - rich people donating money get to decide what animals are displayed but if we lower budget and rely on tickets and gift shop PEOPLE WILL GET TO SEE THE ANIMAL THEY WANT TO SEE AND NOT THE ONES DONORS DECIDE UPON WHICH ARE EXOTIC. ( it is fair to say question was not framed right )
C) is the only option that says that still might not work because without that money some animals will be sold and won't be able to GET NEW EXHIBITS which are needed to get animals people want to see.