填空求讲解.“You ought to have given them some advice.” “（ ）,but who cared what I said?”

填空求讲解.“You ought to have given them some advice.” “（ ）,but who cared what I said?”
A.So ought I
B.So I ought
C.So I have
D.So I did
我选A,但答案选D,求讲解.