向各位即将考试的TX请教一道语法题啊

Q29: PP78.

As it is with traditional pharmacies, online drugstores rely on prescriptions to be successful, since it is primarily prescriptions that attract the customers, who then also buy other health-related items.

A.      As it is with traditional pharmacies, online drugstores rely on prescriptions to be successful

B.       As with the case of traditional pharmacies, online drugstores rely on prescriptions to have success

C.      As is the case with traditional pharmacies, prescriptions are the cornerstone of a successful online drugstore

D.      As traditional pharmacies, so online drugstores rely on prescriptions to be successful

E.       Like traditional pharmacies, the cornerstone of a successful online drugstore is prescriptions

对这个题目没啥思路

B具体错在什么地方？ 个人觉得不是比较

C还原成什么？