求解题目

scholar

Although many brands of gasoline are sold on Haibei island, gasoline companies there get all of the refined gasoline they sell from Haibei seaport’s only storage tank, which is always refilled with the same quality of gasoline. Therefore, the brands of gasoline for sale on Haibei may be different in name and price, but they are identical in quality. The conclusion depends on which of the following assumptions?
A .when tankers make gasoline delivery at Haibei seaport, the storage tank an Hailed always receives the same quality of gasoline as that in the preceding delivery.
B. if any gasoline company on Haibei alters the quality of its gasoline before sale, the other gasoline companies also use methods before sale that result in the same change in the quality of their gasoline. 我个人觉得选A 答案选B 还望点拨！