This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Physiological changes in pregnancy : \nSelect and explain. \nA. Decreased residual volume, B. Decreased GFR, C. Decreased Cardiac output, D. Increased Haematocrit', 'role': 'user'}, {'content': "Answer: A \nExplanation: *The functional residual capacity and residual volume are decreased due to elevated diaphragm. GFR increases by 50% Cardiac output increases by 40% Hemoglobin and hematocrit decreases. Reference : William's Textbook of Obstetrics 24th edition page 62", 'role': 'assistant'}]