This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Iron deficiency anemia, Subject name: Pathology
Hepcidin is secreted by which of the following? 
Select and explain. 
A. Kidney, B. Bone marrow, C. Duodenum, D. Liver
D: Liver
Answer: D: Liver 
Explanation: Hepcidin A small circulating peptide that is synthesized and released from the liver in response to increases in intrahepatic iron levels Plays a central role in iron metabolism Regulates iron absorption in duodenum