Which of the Following Statements About the Absolute Refractory Period

Which of the following statements about the absolute refractory period of cardiac muscle cells is true?

A) It lasts almost as long as the resultant period of contraction of the cells
B) It is much longer than the refractory period of skeletal muscle cells
C) It allows for tetanic contractions of the heart to occur to assure smooth, coordinated ejection of blood from the ventricles
D) Both it lasts almost as long as the resultant period of contraction of the cells and it is much longer than the refractory period of skeletal muscle cells are true
E) All of the choices are true