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': 'The gold standard test to diagnose PNH is: \nSelect and explain. \nA. Bone marrow study, B. Sucrose hemolysis test, C. Flow cytometry, D. Genetic study', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The gold standard test to diagnose PNH today is flow cytometry. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 884', 'role': 'assistant'}]