This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'For doing ABG, which of the following is used? \nSelect and explain. \nA. Whole blood, B. Plasma, C. RBC, D. Serum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a: (Whole blood)Whole arterial blood is taken for ABG.', 'role': 'assistant'}]