According to this passage: 'A backdraft occurs when a ventilation-limited fire is suddenly supplied with oxygen. The result is a rapid, explosive combustion event.' What is the PRIMARY cause of a backdraft?
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A
Excess fuel with insufficient oxygen suddenly cooling the fire
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B
A ventilation-limited fire receiving a sudden oxygen supply
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C
A fully-developed fire losing its water supply
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D
A structural collapse that introduces fresh air to the structure