The Cardiac Output Is the Volume of Blood That Is

The cardiac output is the volume of blood that is pumped out of the ventricles of the heart in the time interval of one minute. What factor most limits a person's maximal increase in cardiac output during exercise?

A) the rate at which oxygen is delivered to the cardiac muscle cells
B) the time available to fill the heart chambers with blood as the heart rate increases
C) the time it takes for electrical impulses to reach all parts of the heart
D) the total amount of blood in an individual
E) the rate at which cardiac muscle contracts