单项选择题

Questions 17~20 are based on a conversation between a mother and her son about a funny thing happened to their friend Lyn. You now have 20 seconds to read the questions 17~20. The mother said, "I haven’t the faintest idea. "What does that mean

A.I don’t know what to do.
B.I haven’t found any idea.
C.I have no plan.
D.I don’t know at all.