A Reason That Muscle Twitches Become Progressively Stronger in Treppe

A reason that muscle twitches become progressively stronger in treppe is

A) Ca₂+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it.
B) ATP is regenerated faster than it is consumed.
C) myosin heads show faster and faster power strokes.
D) more and more acetytlcholine is released with each stimulus.
E) as the muscle warms up, aerobic respiration is accelerated.