请教OG10-9,OG10-11

9. Astronomers at the Palomar Observatory have discovered a distant supernova explosion, one that they believe is a type previously unknown to science.

(A)
                    that they believe is

(B)
                    that they believe it to be

(C)
                    they believe that it is of

(D)
                    they believe that is

(E)
                    they believe to be of

答案是E, A和B没有省略that,请问C,D,E怎么分析对错呢？

(A)
                        Based on accounts of various ancient writers

(B)
                        Basing it on various ancient writers' accounts

(C)
                        With accounts of various ancient writers used for a basis

(D)
                        By the accounts of various ancient writers they used

(E)
                        Using accounts of various ancient writers

答案是E,请问A为什么不对？、

谢谢！