Which Statement About Fast-Twitch Fibers Is True

Multiple Choice

Which statement about fast-twitch fibers is true?

A) They are more common in the leg muscles of champion sprinters than in champion marathon runners.
B) They have more mitochondria than slow-twitch fibers in the same muscle.
C) They fatigue less rapidly than slow-twitch fibers do.
D) Their abundance is more a product of training than of genetics.
E) They are more common in postural muscles than in finger muscles.