—Why! I ____ get you on the phone．

— We ______ basketball on the playground when you phoned．

A．didn’t; must have been playing                     B．didn’t; must be playing

C．couldn’t; must have played                          D．couldn’t; must be playing

--- Why! I ________ get you on the phone.

--- We ________ basketball on the playground when you phoned.

[　　]

A．didn't; must be playing

B．couldn't; must be playing

C．couldn't; must have played

D．didn't; must have been playing