Answer:
The correct answer is - option B.
Explanation:
Prior to third trimester mother feels heavier breathing and experience difficulty in breathing normally that is due to the head of the baby present under the one of the rib and pressure on the diaphragm.
This get less due to the shift of the baby as the baby stat to move further into pelvis. Moving of the head of the bay towards down into pelvis helps in making breathing easier.
Thus, the correct answer is - option B.