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
The property of protein to absorb UV rays of light is due to: 
Select and explain. 
A. Peptide bond, B. Imino group, C. Disulfide bond, D. Aromatic amino acid
D: Aromatic amino acid
Answer: D: Aromatic amino acid 
Explanation: Aromatic amino acids:-
Amino Acid Absorb UV Light: 
Amino Acids which absorb 250-290 nm (Maximum at 280 nm) UV light are tryptophan, phenylalanine, tyrosine. Maximum absorption of UV light by tryptophan. 
Remember: 

Aromatic amino acids absorb UV light. 
Amino acids are colorless because, they do not absorb visible light.