Which Statement About Fast-Twitch and Slow-Twitch Fibers Is False

Which statement about fast-twitch and slow-twitch fibers is false?

A) Athletes in different sports show different percentages of slow-twitch muscle fibers.
B) Differences in the amount of myoglobin and number of mitochondria contribute to the differences in the color of fibers.
C) A single muscle may contain fast- and slow-twitch fibers.
D) Fast-twitch fibers fatigue slowly.
E) The proportion of fast-twitch and slow-twitch fibers in muscle can be altered using different types of athletic training.