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

题目

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.

答案

这里我也是.ought在此不作情态动词用.又根据后者说的话中有cared一词,确定为一般过去式,所以选D