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: Medicine
Which of the following doesn't have any effect on pancreatic secretion? 
Select and explain. 
A. Cck, B. Gastrin, C. Secretin, D. Gastric inhibitory polypeptide
D: Gastric inhibitory polypeptide
Answer: D: Gastric inhibitory polypeptide 
Explanation: Answer- D. Gastric inhibitory polypeptideCCK- As chyme floods into the small intestine, cholecystokinin is released into blood and binds to receptors on pancreatic acinar cells, ordering them to secrete large quantities of digestive enzymes.Secretin-The predominant effect of secretin on the pancreas is to stimulate duct cells to secrete water and bicarbonate.Gastrin- Stimulate acid secretion by the parietal cell, gastrin stimulates pancreatic acinar cells to secrete digestive enzymes.