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': "Best way to prevent hypotension during spinal anesthesia \nSelect and explain. \nA. Preloading with crystalloids, B. Mephentermine, C. Dopamine, D. Tredelenbug's position", 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Preloading with crystalloids', 'role': 'assistant'}]