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: Microbiology
[{'content': 'Which of the following methods is adopted for \nscreening HIV infection? \nSelect and explain. \nA. Virus isolation, B. Western blot followed by ELISA, C. ELISA followed by western blot technique, D. Polymers chain reaction', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]