A. True. Cardiac output before exercise = 250 mL/min/50 mL/L blood = 5 Lblood/min.Cardiac output during exercise = 1500 mL/min/150 mL/L blood = 10 L blood/min.Physical exercise increased cardiac output by 10 L blood/min/5 L blood/min = 2times.B. False. Stroke volume = CO/HR. The value was the same {= 0.083L) for bothbefore and during physical exercise.C. True. Most of the oxygen was carried by hemoglobin. Reduction inhemoglobin's affinity caused an increase in the amount of oxygen released from theblood to tissues. From the data, it can be seen that there was a 3 time increase inoxygen released to the tissues during exercise ( 150 mL/L blood /50 mL/L blood).D. False. From the data above, it can be concluded that the change in cardiac outputduring exercise was caused by the change in heart rate (120 beats/min compared to60 beats/min) but not caused by the change in stroke volume (Stroke volume =CO/HR. The value was the same for both before and during exercise = 0.083 L).Reference:Guyton, A.C and Hall, J. E., 2006. Textbook of medical physiology. ElsevierSaunder.