Which of the following fuel oil characteristics establishes the danger point when transferring, pumping, and firing procedures are concerned?（）

A.severe electrical storm
B.fire on the pier
C.fire on the ship
D.any of the above

A.1% to 3%
B.1% to 2%
C.4%
D.2% to 4%

A.bunker at a normal rate
B.check for kinks in hose
C.close valves slowly
D.shut valves before topping off