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: Surgery
[{'content': 'Critical pH in Mendelson syndrome - \nSelect and explain. \nA. 2.5, B. 3, C. 3.5, D. 4', 'role': 'user'}, {'content': 'Answer: A \nExplanation: • Critical pH value: 2.5\n• Gastric pH of 2.5 or less with a gastric contents volume greater than 25 ml are critical values.\n• Maximum pulmonary damage is achieved at an aspirate pH value of 1.5.', 'role': 'assistant'}]