This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Physiology
Iron is absorbed predominantly in the 
Select and explain. 
A. Stomach, B. Duodenum, C. Ileum, D. Colon
B: Duodenum
Answer: B: Duodenum 
Explanation: Iron absorption occurs predominantly in the duodenum and upper jejunum ( Muir and Hopfer, 1985) (Figure 1). The mechanism of iron transpo from the gut into the bloodstream remains a mystery despite intensive investigation and a few tantalizing hits. Ref: guyton and hall textbook of medical physiology 12 edition