<prompt> 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:The lying down positionThe sitting positionThe standing positionAny position, as long as the post - flight recording is made in the same position  <response>: Ans. a The lying down positionRef: Guyton, 13th edp.566Gravity factor is totally eliminated in spaceSo, for comparison preflight BP should be taken in the lying down position 