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
[{'content': 'Position with least vital capacity in G.A. \nSelect and explain. \nA. Trendelenburg, B. Lithotomy, C. Prone, D. Lateral', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Trendelenburg In trendelenburg position, head end is lowered so due to gravity and weight of intra-abdominal viscera, diaphragm is at its highest level causing compression of lungs; so vital capacity is lowered.', 'role': 'assistant'}]