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': 'In periapical X-ray, the radiodensity of the root is seen as \'Fast break" \nSelect and explain. \nA. Bifurcation of canal, B. Calcification of canal, C. Excessive curvature of root canal, D. Meeting of canals', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]