Which of These Activities Is Involved in the Process of Muscle

Multiple Choice

Which of these activities is involved in the process of muscle relaxation?

A) Acetylcholinesterase promotes the concentration of acetylcholine to allow the muscle membrane to return to resting potential.
B) Ca²⁺ is actively taken up by the lateral sacs of the sarcoplasmic reticulum when there is no longer a local action potential.
C) The cross bridges from the thick filaments bind to the thin filaments and bend in such a way as to return the filaments to their original resting position.
D) ATP becomes unavailable.