求解一道语法题

While digging in the Egyptian desert, huge fossil bones have been found by
paleontologists, which appears to have been the second most massive dinosaur that ever lived.

A. huge fossil bones have been found by paleontologists, which appears to have been
B. huge fossil bones have been found by paleontologists, which appear to be from
C. it appears that paleontologists have found huge fossil bones that are from
D. paleontologists have found huge fossil bones from what appears to be
E. paleontologists have found huge fossil bones, which are from what appear to be

pls give reasoning between D and E

答案：D

D 中为什么用APPEARS 啊？？ BONES 不是复数吗?