How long will you be staying?- I don’t know. .A. That’s OKB. Never mindC. It depend

问题补充：

--- How long will you be staying?

--- I don’t know. .

A. That’s OK

B. Never mind

C. It depends

D. It doesn’t matter

答案：

A. That’s OK

B. Never mind

C. It depends

D. It doesn’t matter

解析：

根据句意可以得知，不清楚停留多长时间，因此用It depends.（看情况而定）