Skeletal muscle tissue is found near the bones of the skeleton. These muscles are controlled by the nervous system and allow movement to occur. Smooth muscle tissue is predominantly found in the inner lining of many organs, such as the stomach and intestinal tract. Smooth muscle tissue allows organs to contract on their own. Cardiac muscle tissue is found in the heart. Cardiac muscle also contracts on its own, and it helps the heart beat properly.

This information shows that
A.
the tissues within a living organism are always the same.
B.
parts of living organisms are not organized in any way.
C.
the tissues within a living organism must always be different.
D.
parts of living organisms are organized by their function.