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': 'Round, ribbon-shaped, ovoid, bowling pin and kidney-bean are all types of root canals seen on \nSelect and explain. \nA. Oblique section, B. Longitudinal section, C. Sagittal section, D. Cross section', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]