Closing the door during a fire is crucial as it limits the oxygen available to the fire, slowing its spread. This action contains the flames within the room and allows for safer evacuation and response. Therefore, the best choice is B: It limits the oxygen available to the fire.
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Closing the door during a fire helps to slow its spread primarily by limiting the oxygen available to the fire. This action also helps contain the flames and heat, preventing them from spreading to other areas. Thus, it is a crucial safety measure during a fire emergency. ;