Which activity is most likely to use fast twitch fibers? A rabbit scurries into its burrow as a predator approaches. A horse pulls a wagon loaded with wheat from the fields. A dog walks alongside its owner on the beach. A human swims laps in a pool for close to an hour.

The correct answer would be:

a. A rabbit scurries into its burrow as a predator approaches.

Fast twitch fibers are fibers that use anaerobic metabolism to create fuel, they are better at generating short bursts of strength or speed than slow muscles. However, they fatigue more quickly.