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': 'Epidemiological studies of H. Pylori are done by using - \nSelect and explain. \nA. Urea-breath test, B. Serological markers, C. Culture, D. Gastric-biopsy urease test', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]