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': 'The following OPG best indicates \nSelect and explain. \nA. Combination syndrome, B. Excessive maxillary ridge resorption, C. Christensen’s phenomenon, D. Anterior ridge preservation syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: OPG showing features of combination syndrome – overhanging maxillary tuberosity, extensive\xa0mandibular ridge resorption, extrusion of lower anterior teeth.', 'role': 'assistant'}]