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': "McCall's festoons are \nSelect and explain. \nA. Also called Stittman's Clefts, B. Due to poor oral hygiene, C. Congenital abnormality, D. Due to trauma from occlusion", 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]