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
Which of the following can be viewed on a conventional radiograph? 
Select and explain. 
A. Buccal curvature of roots, B. Gingival fibers, C. Calcification of canals, D. Periodontal ligament
C: Calcification of canals
Answer: C: Calcification of canals 
Explanation: Calcification of canals. Buccal curvature cannot be seen from the conventional radiographs. Gingival fibers and the periodontal ligament, being connective tissues, are radiolucent radiographically.