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': 'Residual volume is best measured by ? \nSelect and explain. \nA. Body plethysmography, B. Helium dilution method, C. Spirometry, D. All of above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer- A. Body plethysmographypulmonary plekysmographs are commonly used to measure the functional residual capacity (FRC) of the lungs - the volumein the lungs when the muscles of respiration are relaxed - and total long capacity', 'role': 'assistant'}]