— How about buying an iPhone 4s for your mother’s birthday?

— Oh, maybe it’s too expensive, Dad. Do you know _______?

A．how much does it cost

B．how much it costs

C．how much it cost

D．how much did it cost

Maybe you could __________              [ ]

A. call up him                    

B. call him up      

C. called him up                  

D. calling up him