What difference between slow twitch and fast twitch muscle fibers relates most to their difference in function?

A. Fast twitch fibers have a richer blood supply than slow twitch fibers.
B. Slow twitch fibers contain more mitochondria than fast twitch fibers.
C. Slow twitch fibers do not require oxygen for energy, but fast twitch fibers do.
D. Fast twitch fibers are found in large muscles, unlike slow twitch fibers.

The slow-twitch muscle has a characteristic red color, this is because is rich in myoglobin and mitochondria. Also is dense in capillaries. It uses an oxidation reaction involving oxygen and fat or carbohydrates. This fibers contract with little force but for long periods.

The fast-twitch muscle has great strength but can only hold it for short periods. It is called white muscle because is less dense in mitochondria and myoglobin and work with anaerobic reactions.

The muscles in your body are a mixture of both types.

Taking into consideration all this, A, C, and D are false, and B is true.