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: Biochemistry
Which of the following is luminous? 
Select and explain. 
A. Porphyrin, B. Zymogen, C. Chromatin, D. Albumin
A: Porphyrin
Answer: A: Porphyrin 
Explanation: Porphyrins are colored and fluorescent wherase porphyrinogens are colorless.- When porphyrins dissolved in strong mineral acids or in organic solvents are illuminated by ultraviolet light, they emit a strong red fluorescenceQ.- The double bonds joining the pyrrole rings in porphyrin are responsible for characteristic absorption & fluorosence.- Soret band: - The sharp absorption band near 400nm. shown by porphyrin solution (in 5% HC1)- Is characteristic of all porphyrins regardless of the side chain present.