[求助] prep2-39 old

Raymond_GMAT

As it is with traditional pharmacies, on-line 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, on-line drugstores rely on prescriptions to be successful

(B) As with the case of traditional pharmacies, on-line drugstores rely on prescriptions to have success

(C) As is the case with traditional pharmacies, prescriptions are the cornerstone of a successful on-line drugstore

(D) As traditional pharmacies, so on-line drugstores rely on prescriptions to be successful

(E) Like traditional pharmacies, the cornerstone of a successful on-line drugstore is prescriptions

答案是C。
我想问的是since it is primarily prescriptions that 。。。。。中it指代什么？

Gail小M

LZ..有没有可能it is...that...只是表强调的...