All of the following are part of the fire triangle EXCEPT（）.

A.opened and burned material removed
B.left closed with vents off until all boundaries are cool
C.checked for oxygen content
D.doused with water to prevent reflash

A.use all CO₂ available to cool the surrounding area
B.stand by with water or other agents
C.thoroughly ventilate the space of CO₂
D.jettison all burning materials

A.Electrical cut off switch
B.A fusible link
C.Manual cut off switch
D.A water spray actuator