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: Social & Preventive Medicine
[{'content': 'Which of the following is true about tuberculin test? \nSelect and explain. \nA. It gives the immune status of patient, B. It tells about prior exposure to Mycobacterium tuberculosis only, C. It may be negative in dissociated tuberculosis, D. It is highly positive in a post measles case', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]