Final answer:
The diaphragm elevates approximately 4 cm during pregnancy to accommodate the growing uterus and the fetus, with the closest provided option being 2-3 cm.
Step-by-step explanation:
The diaphragm is a large, dome-shaped muscle that plays a critical role in respiration. During pregnancy, the diaphragm elevates to accommodate the growing fetus. The increase in respiratory minute volume by 50 percent is necessary to meet the oxygen demands of the fetus and handle the increased maternal metabolic rate. The diaphragm elevates approximately 4 cm during pregnancy, which is not among the provided options, so if this is a multiple-choice question and only the provided options are taken into account, the closest correct answer would be (a) 2-3 cm. However, it's important to note that individual variation exists, and the elevation may be slightly different for each pregnant woman.