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
And here is the explaination on OG regarding choice C : Also, the phrase two stars that orbit each other illogically suggests that there are two particular stars causing all the phenomena in question, rather than various sets of stars in various locations.
Just don't understand what's the difference between stars that orbit.... and stars orbiting..... Shouldn't they be the same?
Thank you so much in advance........ | 
