56. Calcium ions are very important for skeletal muscle contraction and are the key to
initiating the transverse bridge cycle. Which of the following statements is correct?
(A) Released through sarcoplasmic reticulum calcium channels
(B) Enter the cytoplasm through the calcium channel of the muscle cell membrane
(C) Enter the cytoplasm through the motor end-plate calcium channel
(D) Recycled to mitochondria by active calcium pump transport