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
An example of chromoprotein is 
Select and explain. 
A. Hemoglobin, B. Sturine, C. Nuclein, D. Gliadin
A: Hemoglobin
Answer: A: Hemoglobin 
Explanation: Chromoproteins: These are proteins with coloured prosthetic groups. Hemoglobin (Heme, red); Flavoproteins (Riboflavin, yellow), Visual purple (Vitamin A, purple) are some examples of chromoproteins.
Reference: Vasudevan 7th  ed, pg 43