This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
Which of the following are metalloporphyrins? 
Select and explain. 
A. Hemoglobin, B. Catalase, C. Bilirubin, D. Cytochrome
A: Hemoglobin
Answer: A: Hemoglobin 
Explanation: Hemoglobin consists of heme and globin.in which heme pa consists of porphyrin ring and metallic iron.Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 271