In the Movies,there Are Often Scenes Where Someone Is Holding

In the movies,there are often scenes where someone is holding a person to prevent them from falling.All of a sudden,the person's grip gives way and the other person falls.What is this most likely due to?

A) The person changes their mind and lets go.
B) Fatigue,following sustained muscle contraction,is apparent when a muscle relaxes even though stimulation continues.
C) A muscle twitch has a contraction period followed by a relaxation period.
D) Some of the muscle fibers contract while others relax at any given time.When more muscle fibers relax than contract,the grip would be broken.
E) The slow-twitch muscle fibers take over after the fast-twitch muscle fibers fail.These do not have the same strength and endurance as the fast-twitch fibers and the person lets go.