Jamieson's proposal was rejected for several reasons, [url]the chief among which was cost[/url].

(A) the chief among which was cost
(B) among which the chief was its cost
(C) the main one was cost
(D) the chief reason of which was its cost
(E) the chief of which was cost

I think A, C and E are correct....how do I chose one?

Also although I eliminated B and D for other reasons I still think its necessary the "its" (its costs)...

Thanks!