关于倒装的一道题 Important _____his discovery was,it was

关于倒装的一道题
Important _____his discovery was,it was regarded as a matter of no account in his time.
A to
B for
C as
D although
求解

Important as his discovery was, it was regarded as a matter of no account in his time.
他的发现虽然很重要，但是在当时却被视为无关紧要。

答案错了 再看看别人怎么说的。