a. Option 3 Trend C. The forearm blood flow falls as part of the general vasoconstriction that helps to maintain arterial blood pressure.
b. Option 3 Trend C. As the blood pools in the lower body due to suction, the filling pressure of the heart decreases and so the cardiac output falls.
c. Option 1 Trend A. During this relatively mild gravitational stress, arterial pressure is quite well maintained by mechanisms that compensate for the shift of blood volume towards the feet.
d. Option 2 Trend B. The shift of blood initiates reflex mechanisms to increase total peripheral resistance to help to maintain arterial pressure.
e. Option 2 Trend B. The diminished blood flow to the kidneys with vasoconstriction related to the fall in cardiac output and output results in the release of renin from the juxtaglomerular apparatus that again helps to maintain arterial blood pressure.