―How much do the pencils cost?                   

―Three pounds        pencils.   

A．by two dozen of                                         B．for two dozen of 

C．by two dozen                                             D．for two dozen   

—How much do the pencils cost?

—Three pounds        pencils.

A．by two dozen of                                         B．for two dozen of

C．by two dozen                              D．for two dozen