I can't go there with you .I have to babysit my sister.该怎么回答A.That right B.thank you C that'sOk

I can't go there with you .I have to babysit my sister.该怎么回答A.That right B.thank you C that's
Ok

C
表示我理解
A 不对,这里没有问你对不对
B不对,又没帮你什么,谢什么谢