This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Psoriasis, Subject name: Dental
[{'content': 'All are nail changes seen in cases of psoriasis except: \nSelect and explain. \nA. Subungual hyperkeratosis, B. Thimble pitting, C. Mees lines, D. Oil drop sign', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Mees lines - seen in Arsenic poisoning Nail changes in psoriasis - MC - Nail pitting/Thimble pitting Most characteristic - oil drop sign/ salmon patch Onycholysis Leukonychia Subungual hyperkeratosis Nail tunnel', 'role': 'assistant'}]