Tom is very short now.His mother wishes that he ________ be tall when he grows up.A.could B.sho

Tom is very short now.His mother wishes that he ________ be tall when he grows up.A.could B.sho
为什么选C不选A,
B should C would D might ,还有wish后面的虚拟表将来A不是也对吗,希望他将来能长高.