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': 'Least common site involvement in psoriasis is – \nSelect and explain. \nA. Scalp, B. Nail involvement, C. CNS involvement, D. Arthritis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Not found in psoriasis\n\nAlopecia (despite the involvement of scalp)\nFace involvement (though scalp lesion can extend on forehead\nMucosal involvement\n\nUncommon in psoriasis\n\nJoint involvement (5-10%)\nPruritis', 'role': 'assistant'}]