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': 'Halo effect in an X-Ray is seen in which condition \nSelect and explain. \nA. Horizontal Root Fracture, B. Acute apical abscess, C. Acute apical periodontitis, D. periapical periosteitis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Halo effect is typical of vertical root fracture. As that is not in the option next best choice is periapical periosteitis', 'role': 'assistant'}]