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': 'Sour taste is mediated by \nSelect and explain. \nA. Na+ selective channel (ENac), B. G - protein coupled receptors, C. H+ ions permeable to ENaCs, D. Glutamate receptors', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Salt ⇒ mediated by Na+\xa0selective channel (ENaC)\nSour ⇒\xa0mediated by H+\xa0ions permeable to ENaCs\nBitter, sweet, umami ⇒\xa0mediated by G-protein coupled receptors', 'role': 'assistant'}]