TTGWD1-16

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.

1. huge fossil bones have been found by paleontologists, which appears to have been
2. huge fossil bones have been found by paleontologists, which appear to be from
3. it appears that paleontologists have found huge fossil bones that are from
4. paleontologists have found huge fossil bones from what appears to be
5. paleontologists have found huge fossil bones, which are from what appear to be

在D和E中犹豫不决，选D难道是因为appear对应后面的the second most massive dinosaur，所以用单数，还请牛人指教。

E中的appear 和它所修饰的the second most massive dinosaur 明显单复数不对称啊

而且 和D比起来 E实在太罗嗦了 which are from what appear to be the second most massive dinosaur that ever lived

这都用了好几个从句了 一点都不紧凑

楼上仁兄的回答很全面了。但偶认为楼主之所以在细节上如此纠结，恐怕是因为忘记了ＧＭＡＴ语法的几大原则：简洁　　平行　　逻辑正确　；浅见，还请ｎｎ指教！