If the postfix equvilant of the statment if c then x else y is cxy#, then the postfix form amn+mn-ab#ba-#?

(A) Has no syntactically Valid prefix equvilant
(B) is equvilant to if a then if mn then m-n else a-b else b-a
(C) is equvilant to if a then mn then m-n else a-b else b-a
(D) is equvilant to if a then m-n else if m+n then a-b else b-a