This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
[{'content': 'Hemoptysis is said to be massive when it exceeds what amount in 24hours? \nSelect and explain. \nA. 400mL, B. 500mL, C. 600mL, D. 800mL', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Massive hemoptysis is generally defined as expectoration of over 600 mL of blood within a 24hour period. It is a medical emergency associated with a moality rate of 30 to 50%. Ref: Harrison; 20th edition pg 233', 'role': 'assistant'}]