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 can be viewed on a conventional radiograph? \nSelect and explain. \nA. Buccal curvature of roots, B. Gingival fibers, C. Calcification of canals, D. Periodontal ligament', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Calcification of canals. Buccal curvature cannot be seen from the conventional radiographs. Gingival fibers and the periodontal ligament, being connective tissues, are radiolucent radiographically.', 'role': 'assistant'}]