求助一道语法题

The Achaemenid empire of Persia reached the Indus Vally in the fifth century B.C.,bingring the Aramaic script with it,from which was derived both northern and southern Indian alphabets.
A.the Aramaic script with it,from which was derived both northern and
B.the Aramaic script with it,and from which was derived both the northern and the
C.with it the Aramaic script ,from which derive both the northern and the
D.with it the Aramaic script ,from which derives both northern and
E.with it the Aramaic script ,and deriving from it both the northern and

一个疑问。为什么这个句型里要倒装呢？
假如说a起源于b。。应该是a,which derives from b吗？
那b起源于a，应该是a,from which b derives吗？还是a, from which derives b？ 还是都可以呢？倒装是必须的吗？