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': 'Wiggly appearance of the master cone in the root canal suggests: \nSelect and explain. \nA. Long cone in the canal, B. Short cone in the canal, C. Thick cone in the canal, D. Thin cone in the canal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: If the cone goes to length and radiographically exhibits a wiggly or S-shaped appearance, the cone is too small for the canal and a larger cone must be selected.', 'role': 'assistant'}]