This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Preoperative assessment and monitoring in anaesthesia, Subject name: Anaesthesia
[{'content': 'Lightly anaesthetized patient in the lithotomy position (?spontaneously breathing):which of the following is true? \nSelect and explain. \nA. Marked reduction in vital capacity, B. Increased FRC, C. Normal alveolar ventilation, D. Residual volume & closing volume equal', 'role': 'user'}, {'content': 'Answer: D \nExplanation: no change to VC decrease in FRC decreased alveolar ventilation CV approaches FRC', 'role': 'assistant'}]