Which of the following should not be used when trying to escape a fire

A．the only way of escaping a fire
B．the best place if you want to get out
C．one of the possible ways to escape a fire
D．safer than any other ways of escaping a fire

A．breathing smoke is not good for one's health
B．smoke will enter the room by an open window
C．it is difficult for fresh air to reach the second floor
D．it is better to keep your head low when there is smoke in the room