A Woman in Labor Is Breathing into a Mouthpiece Just

Multiple Choice

A woman in labor is breathing into a mouthpiece just before the start of her regular contractions.As she inhales,a valve opens,and gas is released.She continues to inhale the gas slowly and deeply until the contraction starts to subside.When the inhalation stops,the valve closes.Which statement regarding this procedure is correct?

A) The application of nitrous oxide gas is not often used anymore.
B) An inhalation of gas is likely to be used in the second stage of labor,not during the first stage.
C) An application of nitrous oxide gas is administered for pain relief.
D) The application of gas is a prelude to a cesarean birth.