Final answer:
The diaphragm elevates 3-4 cm during pregnancy to accommodate the growing fetus, making option B) 3-4 cm the correct answer. This elevation helps the mother breathe as the fetus grows bigger and exerts more pressure on her diaphragm. The correct option is b.
Step-by-step explanation:
The diaphragm elevates during pregnancy to accommodate the growing fetus and the increasing demands on the mother's body. During the second half of pregnancy, the respiratory minute volume increases by 50 percent due to the fetus's oxygen needs and the mother's higher metabolic rate.
As the uterus grows, it exerts upward pressure on the diaphragm, which can decrease the volume of each breath and cause a sensation of shortness of breath or dyspnea. Towards the end of pregnancy, lightening occurs when the pelvis becomes more elastic and the fetus descends, typically lessening the feelings of dyspnea.
To answer the question: The diaphragm elevates 3-4 cm during pregnancy. This is option B) 3-4 cm. The correct option is b.