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: Pathology
[{'content': 'Ammonia causes \nSelect and explain. \nA. Increase in plaque formation, B. Increase in calculus formation, C. Decrease in plaque formation, D. Causes precipitation of salivary proteins', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]