So far the majority of cloned animals have suffered from some different serious disorders, ______ died soon after birth

1. A.
   many of which
2. B.
   many of whom
3. C.
   many of them
4. D.
   many of that

So far the majority of cloned animals have suffered from some different serious disorders, ______ died soon after birth.

A. many of which    B. many of whom C. many of them    D. many of that