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': "The following are true of Mendelson's syndrome – \nSelect and explain. \nA. Critical volume of aspirate is 50 mls, B. Critical pH of gastric aspirate is 1.5, C. Onset of symptoms generally occurs within 30 minutes, D. Steroids have been shown to improve outcome", 'role': 'user'}, {'content': "Answer: C \nExplanation: Symptoms of Mendelson's syndrome generally occurs within 30 minutes of aspiration.\nCritical pH is 2.5 and critical volume is 25 ml.\nUse of corticosteroid is generally not recommended.", 'role': 'assistant'}]