An aircraft has indicated that he wants yo

问题：

An aircraft has indicated that he wants you to change course and follow him. You cannot comply because of an emergency on board. Which signal should you make?（）

A.Fire a red flare at night or a red smoke signal by day

B.Send the Morse signal "N" by flashing light

C.Make a round turn (360°) and resume course

D.Make an "S" turn (hard right then hard left) and resume course