This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
The most significant change in maternal lung volume that occurs in the third trimester of pregnancy includes. 
Select and explain. 
A. Decrease in vital capacity, B. Increase in residual volume, C. Decrease in functional residual capacity, D. Decrease in closing capacity
C: Decrease in functional residual capacity
Answer: C: Decrease in functional residual capacity 
Explanation: With enlargement of uterus, diaphragm is forced cephalad that decreases FRC.