A ship must have a self-contained breathing apparatus to be used as protection from gas leaking from a refrigeration unit. To meet this requirement，you may use（）.

A.a gas mask certified by the Mine Safety and Health Administration
B.the same self-contained breathing apparatus required with the fireman's outfit
C.an oxygen breathing apparatus，provided that the device has been inspected within three years
D.a portable ventilation system that will provide a complete change of air every three minutes