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: Pharmacology
[{'content': 'Histamine blocker in stomach act through : \nSelect and explain. \nA. Decreasing cAMP in stomach, B. Increasing cAMP in stomach, C. Increasing IP3 in stomach, D. Decreasing IP3 in stomach', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]