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': 'Flowcytometry is best used in the measurement of: \nSelect and explain. \nA. Serum level of LDH, B. T4, T8 serum ratio in AIDS, C. To count the RBCs in blood, D. Separation of proteins', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]