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: Skin
[{'content': 'Mucosa is involved in: \nSelect and explain. \nA. Psoriasis, B. Lichen planus, C. Alopecia, D. Scabies', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e., Lichen planus', 'role': 'assistant'}]