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': 'Most sensitive method for detecting low density microfilaraemia \nSelect and explain. \nA. Mass blood survey, B. DEC Provocation test, C. Membrane filter concentration method, D. Xenodiagnosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]