---How do you come to school, Jimmy?

---        ．Usually by bike，but I take a bus in bad weather．

A．Don’t mention it

B．It doesn’t matter

C．Forget it

D．It depends

Finding information in today's world is easy.  The____is how you can tell if the information you get is

useful or not.[ ]

A. ability     

B. competition

C. challenge    

D. knowledge