- Sorry Frank. I’m busy today. I can’t go swimming with you. .A. No problem B. Yo

问题补充：

--- Sorry, Frank. I’m busy today. I can’t go swimming with you.

--- .

A. No problem

B. You’re welcome

C. That’s all

D. Never mind

答案：

A. No problem

B. You’re welcome

C. That’s all

(答案→)D. Never mind

解析：No problem 没问题； You’re welcome欢迎你，不客气； That’s all就这样，如此而已；Never mind没关系。根据上文，抱歉，弗兰克。我今天忙。我不能和你去游泳了。可知选D为最佳答案。