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: Medicine
[{'content': 'Screening tests for cell defects : \nSelect and explain. \nA. Isohemagglutinin titers, B. CD4 levels, C. Nitroblue tetrazolium dye test, D. Candida albicans intraden-nal skin test', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]