What do you think of my new dress?（）A.It's on sale B.It's a birthday present for you C

What do you think of my new dress?（）A.It's on sale B.It's a birthday present for you C.You really need one D.It looks very good on you

When someone asks for your opinion on their new dress, the most appropriate and polite response is to compliment their appearance. Among the options, "It looks very good on you" directly addresses how the dress suits them, which is the natural way to respond to such a question.

D. It looks very good on you

This choice focuses on the person wearing the dress rather than the dress itself (options A and B) or making an unrelated statement (option C). Complimenting how the dress looks on them shows you've noticed and appreciate their choice.