11. 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

doubt 后面加whether ,或者that,有什么区别来者？

我觉得那个that指代的是前面的 body ，你不能说 body 是man ，而只能说body 是属于man的，所以用 that of！

谁能解释一下doubt+that或whether的区别？