A.as it warms up it becomes heavier than air
B.the way it reacts with sea water
C.the strong odor it produces
D.its low temperature causes frostbite or freezing

A.the introduction of inert gas into a tank with the object of reducing the oxygen content to below 8% by volume
B.the introduction of inert gas into a gas free tank for the purpose of reducing the oxygen content to below 8% by volume
C.the introduction of inert gas into a cargo tank during cargo discharge to replace the volume of discharged cargo
D.All of the above