Final answer:
During the second stage of labor, the breathing technique taught by a Lamaze childbirth educator is to push down with an open glottis, which assists in the safe delivery of the baby.
Step-by-step explanation:
The Lamaze childbirth educator is teaching the breathing technique most appropriate during the second stage of labor. The correct technique is Push down with an open glottis (Option 3). This method involves the laboring person using controlled breaths to push effectively and help move the baby down the birth canal. The second stage of labor is when the baby is expelled from the uterus, and this involves the mother pushing with the aid of compressed abdominal muscles. The open-glottis method of pushing can help prevent undue pressure and stress on the mother's body and decrease the risk of oxygen deprivation to the baby during this critical time.