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: Radiology
[{'content': 'Which of the following is best suited for detection of calculi in the submandibular gland? \nSelect and explain. \nA. Lower true occlusal, B. Lower topographic occlusal, C. Lower oblique occlusal Vertex occlusal, D. Vertex occlusal', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]