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': 'Which of the following liners when exposed to oral fluids result in diminishment of their antimicrobial effectiveness? \nSelect and explain. \nA. MTA, B. Calcium hydroxide, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: MTA and calcium hydroxide undergo a transformation of hydroxide to calcium carbonate from exposure to carbon dioxide in the blood and oral fluids, causing their antimicrobial effectiveness to diminish.', 'role': 'assistant'}]