Which of the following gases represents the greatest threat to personnel safety in an engine room where the exhaust is leaking from a diesel engine?（）

A.at a maximum rate of two ounces per day
B.after mixing with an equal quantity of fresh water
C.if gather during or immediately after a hard rain
D.under no circumstance

A.wood
B.oil
C.electrical equipment
D.magnesium

A.skimmers
B.straw
C.dispersants
D.sawdust