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: Dental
[{'content': 'The concentration of constituents in saliva depends on: \nSelect and explain. \nA. Nature of stimulus., B. Duration of the stimulus., C. Rate of flow., D. Differential gland contribution.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Other important factors affecting the composition\xa0of saliva are flow rate, differential gland contribution,\xa0circadian rhythm, duration of stimulus, nature of stimulus and diet.\nThe concentration of constituents in saliva depends\xa0only on the rate of flow and not on the nature of\xa0stimulus.', 'role': 'assistant'}]