Although the coordination of monetary policy can help facilitate the orderly financing of existing imbalances, it is unlikely that its effect on their size is significant, in the absence of an appropriate fiscal adjustment.

(A) it is unlikely that its effect on their size is significant
(B) it is unlikely that the size of their effect would be significant
(C) affecting their sizes are not likely to be significant
(D) the significance of their effect on its size is unlikely
(E) its effect on their size is not likely to be significant

OA is E

I agree likely to be is a correct idiom but Whats wrong with A? Also, "its" is a possessive pronoun . Can a possessive pronoun refer back to a subject/object noun?