In ancient times, Nubia was the principal corridor where there were cultural influences transmitted between Black Africa and the Mediterranean basin.

(A) where there were cultural influences transmitted

(B) through which cultural influences were transmitted

(C) where there was a transmission of cultural influences

(D) for the transmitting of cultural influences（B）

(E) which was transmitting cultural influences

Choice A is imprecise and unidiomatic. In choice B, the best answer, through which suggests the movement or passage of cultural influences between the ends of the corridor and so provides a clearer description of Nubia’s role in the ancient world. Choices C and D, like A, are unidiomatic and needlessly indirect. In choice E, which refers to corridor, thereby suggesting somewhat imprecisely that the corridor itself, not the civilizations it connected, was transmitting cultural influences Also, transmitted is preferable to transmitting in a description of past events. This is an easy question.

Why A is imprecise and unidiomatic?