The Refractory Period of Cardiac Muscle

The refractory period of cardiac muscle

A) lasts almost as long as the contraction period
B) is much longer than the refractory period in skeletal muscle
C) prevents tetanic contraction of the heart to occur to ensure smooth, coordinated ejection of blood from the ventricles
D) is important for all of the above reasons
E) is important for only reasons a and b