题目选项分析

Fish currently costs about the same at seafood stores throughout Eastville and its surrounding suburbs. Seafood stores buy fish from the same wholesalers and at the same prices, and other business expenses have also been about the same. But new tax breaks will substantially lower the cost of doing business within the city. Therefore, in the future, profit margins will be higher at seafood stores within the city than at suburban seafood stores.

For the purposes of evaluating the argument, it would be most useful to know whether

【选项】Fish has always cost about the same at seafood stores throughout Eastville and its surrounding suburbs