Question

Which process must occur for a muscle to be able to relax? A. The concentration of calcium in the myofibril must decrease. B. The amount of ATP in the neuromuscular junction must increase. C. A nerve must initiate an action potential in the muscle fiber. D. Myosin and actin must attach to each other.

Answer 1

A

Step-by-step explanation:

Concentration of calcium in the myofibril must decrease.

Answer 2

Relaxation occurs when stimulation of the nerve stops. Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.