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
1 cells of duodenum secrete 
Select and explain. 
A. Secretin, B. Gastrin, C. CCK, D. Motilin
C: CCK
Answer: C: CCK 
Explanation: Enteroendocrine cells (EEC) secrete key gastrointestinal (GI) hormones such as gastric-inhibitory peptide (GIP), cholecystokinin (CCK) and ghrelin that are involved in nutrient sensing pathways and are often implicated in GI pathology. EEC is also known as I cells. Ref: www.pshysoc.org