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': 'A radiograph of the mesial aspect of the mandibular right first molar show 2-3 mm of bone loss, yet clinical probing indicate a pocket depth of 6-8 mm. This discrepancy is probably due to the? \nSelect and explain. \nA. Poor angulation used in taking the radiograph, B. Presence of mandibular tori in the area, C. Presence of mesial bone masking the destruction, D. Presence of facial or lingual bone masking the destruction', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]