All of the following are true except: select one:
a. the diastole is the relaxation phase of the heart beat where the pressure on the walls of the blood vessels is lowest.
b. the systole is the contraction phase of the heart beat where the pressure on the walls of the blood vessels is highest.
c. red blood cells are responsible for gas transport.
d. a centrifuged sample of blood would yield a composition of 45% plasma and 55% cells