Dry chemical extinguishers extinguish class B fires to the greatest extent by（）.

A.heated gases flowing through ventilation systems
B.the transfer of heat across an unobstructed space
C.burning liquids flowing into another space
D.transmitting the heat of a fire through the ship's metal

A.directly outside the space protected by the system
B.as near the gas cylinders as possible
C.in the pilothouse
D.on the main deck near the bow

A.first
B.following control of fire
C.following restoration of vital services
D.only if a threat exists