OG12 SC

69. Once they had seen the report from the medical examiner, the investigators did not doubt whether the body recovered from the river was the man who had attempted to escape from the state prison.   

(A) did not doubt whether the body recovered from the river was

(B) have no doubt whether the body recovered from the river was

(C) had not doubted that the body recovered from the river was

(D) have no doubt whether the body recovered from the river was that of(E)

(E) had no doubt that the body recovered from the river was that of

答案：E

这题从时态上可以理解BD不对，应该用完成时，但想请问一下各位大佬，ACE怎么解析呢？

另外，也不太理解为什么要加that of ？是因为the body 并不能指代the man 而是the body of the man吗？