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: Pathology
[{'content': 'Saw tooth retepegs are seen in \nSelect and explain. \nA. Lichen planus, B. Leukoplakia, C. Pamphigus vulgaris, D. Psoriasis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Histology of Lichen planus:', 'role': 'assistant'}]