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
Color of dried semen becomes yellow to brown. Dried semen stain in clothes is identified by: 
Select and explain. 
A. UV light, B. Spectroscopy, C. Magnifying lens, D. Infrared
A: UV light
Answer: A: UV light 
Explanation: When dried semen is examined under filtered ultraviolet light, they show a fluorescence of a bluish-white colour, which is not specific as other albuminous materials such as nasal, leucorrhoeal discharges and detergents also fluoresce. Fluorescence depends on choline of semen. Ref: The Essentials of Forensic Medicine and Toxicology, 27th edition, Page 369.