Which extinguishing agent is best for use on a magnesium fire?（）

A.Leaves a residue
B.Cost，relative to other agents
C.Breaks down while under prolonged storage
D.Conducts electricity

A.Electrically non-conductive
B.Relatively inexpensive
C.Effective against chemicals containing an oxidizer
D.All of the above

A.Insure the chemical is powdery
B.Replace the cartridge
C.Pressure test the discharge hose
D.Test the pressure gauge for proper operation