This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: SLE, Subject name: Medicine
A young girl is admitted with joint pains and butterfly rash and positive urine proteinuria. The best test for her diagnosis is ? 
Select and explain. 
A. Anti ds-DNA antibody, B. Anti-centromere antibody, C. Antibodies to RNP, D. Antibodies to tRNA synthetase
A: Anti ds-DNA antibody
Answer: A: Anti ds-DNA antibody 
Explanation: Ans. is 'a' i.e., Anti ds-DNA antibody o Association of antibodies with disease activity.# Anti ds-DNA antibody is-increased risk oj nephritis in cases oj SLE.# Anti centromere ab is-limited scleroderma.# Antibodies to RNP is-CNS lupus.# Antibodies to tRNA synthetase-polymyositis with interstitial lung disease.