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': '"Corn-Cob" appearance seen in \nSelect and explain. \nA. Supragingival calculus, B. Subgingival calculus, C. Supragingival plaque, D. Subgingival plaque', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]