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: Forensic Medicine
[{'content': 'Dried semen stains on clothes are identified by: \nSelect and explain. \nA. Spectrometry, B. Ultravoilet rays, C. Infrared rays, D. Magnifying lens', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ultravoilet rays', 'role': 'assistant'}]