This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of nail, Subject name: Dental
[{'content': 'Nail changes are found in about ______ cases of psoriasis: \nSelect and explain. \nA. All, B. One third, C. One half, D. Two third', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Nail involvement is seen in association with all type of psoriasis and is frequently present with psoriatic ahropathy. About half of all patients with psoriasis have fingernail involvement, appearing as punctate pitting, onycholysis, nail thickening, or subungual hyperkeratosis. About 5-10% of patients with psoriasis have associated ahralgias, and these are most often found in patients with fingernail involvement', 'role': 'assistant'}]