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': 'Distance between undersurface of hygienic pontic and gingiva is \nSelect and explain. \nA. 1 mm, B. 1.5 mm, C. 2 mm, D. 2.5 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]