Slow oxidative muscle is often referred to as "red muscle", while fast glycolytic is referred to as "white muscle". What gives slow oxidative muscle its red color?

Explanation:

The skeletal muscle can be distinguished on the basis of their color which depends on the function they perform.

The muscle which is involved in the slow locomotion like the muscles involved in the breathing and chewing are red whereas the muscle which requires instant energy to perform a function is white.

The difference in the colour is due to the fact that the slow muscle requires a continuous supply of oxygen which is carried by the red blood cells. These red blood cells are stored in the muscle by the myoglobins in the muscle.  Due to the accumulation of these red blood cells in the slow oxidative cells therefore they are red in colour.

the correct answer is:

a population changes in response to a change in the environment.