If the pilot believes that his radio has failed, what is the pro

If the pilot believes that his radio has failed, what is the proper procedure he will use to inform the controller of the situation?

A.To set the transponder to 7700 for one minute

B.To set the transponder to 7600 for one minute

C.To make a Mayday call on the radio

D.To set the transponder to 7700 for one minute and then change it to 7600 for 15 minutes or until landing

正确答案是D