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
Secretin 
Select and explain. 
A. Reduces the action of CCK PZ, B. Reduces Gastric secretion, C. Increases Gastric secretion, D. Relaxation of pyloric spincter
B: Reduces Gastric secretion
Answer: B: Reduces Gastric secretion 
Explanation: Secretin is secreted by S cells in the upper pa of the small intestine. Secretin increases the secretion of bicarbonate by the pancreas. It also augments the action of CCK. It decreases gastric acid secretion and May cause contraction of pyloric sphincter.(Ref: Ganong&;s Review of medical physiology, 23 rd edition, page 446 )