This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Biochemistry
Replacing alanine by which amiens acid will increase UV absorbance of protein at 280nm wavelength 
Select and explain. 
A. tryptophan, B. Arginine, C. Guanine, D. Lysine
A: tryptophan
Answer: A: tryptophan 
Explanation: ref : satyanaryana 8th ed