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: Physiology
[{'content': 'Interaction of histamine with  H2 receptor in parietal cell results in \nSelect and explain. \nA. Increase in intracellular Na+ concentration, B. Increase in intracellular CAMP production, C. Increase in intracellular Ca2+ concentration, D. Stimulates IP3 - DAG pathway', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]