这里的oribting到底修饰哪个名词。

237. It seems likely that a number of astronomical phenomena, such as the formation of planetary nebulas, may be caused by the interaction where two stars orbit each other at close range.

(A)  may be caused by the interaction where two stars orbit each other

(B)  may be caused by the interaction between two stars that each orbit the other

(C)
                        are because of the interaction between two stars that orbit each other

(D)  are caused by the interaction of two stars
                where each is orbiting the other

(E)   are caused by the interaction of two stars
                orbiting each other

这里的oribting到底是修饰哪个名词，是stars还是interaction,我觉得是stars，可是为什么有人说是interaction呢..求教。