Which of the Following Is NOT Part of the Explanation

Which of the following is NOT part of the explanation for the all -or -nothing property of an isometric twitch contraction of skeletal muscle?

A) equivalent calcium released by each action potential
B) all -or -nothing property of the action potential generated by a skeletal muscle
C) equivalent calcium reuptake by the sarcoplasmic reticulum
D) equal numbers of crossbridges activated by the calcium released
E) equivalent activation of calmodulin stimulating myosin light -chain kinase activity