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': 'Semen stains on clothes can be identified by: \nSelect and explain. \nA. Infrared rays, B. Magnifying lens, C. Spectrometry, D. Ultraviolet rays', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ultraviolet rays', 'role': 'assistant'}]