This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Scleroderma, Subject name: Medicine
[{'content': 'Screening test for sclerodema? \nSelect and explain. \nA. Anti-nuclear antibody, B. U l- Ribonucleoprotein antibody, C. Anti- L.K.M antibody, D. Anti- topoisomerase antibody', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Anti-nuclear antibody- ANA is the screening method of choice for systemic rheumatic disease such as systemic lupus ehyematosus (SLE), mixed connective tissue disease, Sjogren syndrome, scleroderma, CREST syndrome, rheumatoid ahritis, polymyositis, and dermatomyositis.', 'role': 'assistant'}]