This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Circulation: Arterial Pressure Regulation - Role of Kidney, Subject name: Physiology
[{'content': 'As a part of space-research program, a physiologist was asked to investigate the effect of flight-induced stress on blood pressure. Accordingly the blood pressure of the cosmonauts was to be measured twice: Once before the takeoff and once after the spacecraft entered the designated orbit around the earth. For a proper comparison, the preflight blood pressure should be recorded in: \nSelect and explain. \nA. The lying down position, B. The sitting position, C. The standing position, D. Any position, as long as the post - flight recording is made in the same position', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) The lying down position(Ref: Guyton, 13th ed/p.566)Gravity factor is totally eliminated in spaceSo, for comparison preflight BP should be taken in the lying down position', 'role': 'assistant'}]