This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal System, Subject name: Physiology
[{'content': 'Duodenum and Jejunum secrete ALL EXCEPT \nSelect and explain. \nA. CCK, B. Secretin, C. GIP, D. VIP', 'role': 'user'}, {'content': 'Answer: D \nExplanation: V.I.P. is a inhibitory neurotransmitter found in nerves in the gastrointestinal tract and thus is not itself a hormone.', 'role': 'assistant'}]