each独立主格问题 哪位大牛帮忙解答？

cedric830vi

这是prep2012的一题：
In his experiments with gravity, Isaac Newton showed how the motion of each planet in the solar system results from the combined gravitational pull of the Sun and of all the other planets, each contributing according to their mass and distance from the others.

A. of all the other planets, each contributing according to their
B. of all the other planets, with each of them contributing according to their
C. all the other planets, each of which contributing according to its
D. all the other planets, each contributing according to its
E. all the other planets, each of which contribute according to their

答案是选D，我是想问each引导的独立主格的时候，each of which/them +分词与each+分词有没有什么区别？就是说C中的contributing为什么就不行？ D中的contributing就可以？
求解答！

cedric830vi

明白了 谢谢