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': 'Parietal cells secrets: \nSelect and explain. \nA. Pepsinogen, B. HCI, C. Mucous, D. Pepsin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: HCI', 'role': 'assistant'}]