This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood: RBCs, Anemia, and Polycythemia, Subject name: Physiology
Which is a heme protein - 
Select and explain. 
A. Hemoglobin, B. Catalase, C. Cytochrome, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. is 'd' i.e., All of the aboveo Hemoproteins are proteins which have heme as prosthetic group.o Important hemoproteins are hemoglobin, myoglobin, cytochromes (cytochrome C, cytochrome P450), catalase, peroxidase, tryptophan pyrrolase and nitric oxide synthase.