请选择DCBA9t'C(I(o:c4P7O;IJack and Ketty_______ in the lake. Let’s join them,shall we?1n*^8`-o)Q0`6d
A. swim1n*^8`-o)Q0`6d
B. have swum1n*^8`-o)Q0`6d
C. swam1n*^8`-o)Q0`6d
D. are swimming1n*^8`-o)Q0`6d