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: Medicine
[{'content': 'What percentage of the MDR TB cases are XDR TB, worldwide? \nSelect and explain. \nA. 5%, B. 10%, C. 20%, D. 25%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Probably 10% of the MDR-TB cases worldwide are XDR-TB (extended drug resistant) Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 1341', 'role': 'assistant'}]