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
Hemoglobin is present in : 
Select and explain. 
A. Hydrophilic pockets, B. Hydrophobic pockets, C. Pyrrole rings, D. Cationic ring
B: Hydrophobic pockets
Answer: B: Hydrophobic pockets 
Explanation: Hemoglobin, a tetrameric protein of erythrocytes, transpos O2 to the tissues and returns CO2 and protons to the lungs. The heme in haemoglobin is surrounded by a hydrophobic pocket, which is necessary in order for it to bind oxygen reversibly without undergoing oxidation or other undesirable reactions. Ref: Kennelly P.J., Rodwell V.W. (2011). Chapter 6. Proteins: Myoglobin & Hemoglobin. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.