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': 'As per RNTCP guidelines, Multi drug resistance (MDR) TB is defined as resistance to: \nSelect and explain. \nA. Rifampicin, B. Rifampicin and isoniazide, C. Rifampicin, isoniazide and ethambutol, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Confirmed MDR-TB case: MDR-TB suspect is one who is sputum culture positive and whose TB is due to Mycobacterium tuberculosis that are resistant in-vitro to at least isoniazid and rifampicin (the culture and DST result being from an RNTCP accredited laboratory). Ref: Park 21st edition, page 178.', 'role': 'assistant'}]