This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
True regarding changes in respiratory system in pregnancy 
Select and explain. 
A. Respiratory rate increase, B. Vital capacity remains unchanged, C. Tidal volume increase, D. Total lung capacity increases
C: Tidal volume increase
Answer: C: Tidal volume increase 
Explanation: Respiratory rate/min 15 15 UnaffectedVital capacity 3200 3300 Almost unchangedTidal volume (ml) 475 675 +40%Residual volume (ml) 965 765 -20%Total lung capacity 5000 4750 -8%