Answer:
Organ level– an organ is a structure composed of at least two different tissue types that perform a specific function within the body. Examples include the brain, stomach, and liver. Complex functions begin to emerge at this level.
Explanation:
Skeletal, smooth, and carbiac. Carbiac makes up the heart.
D. The discoveries confirmed many but not all of the classifications that were based on observable traits, and scientists revised classifications when necessary.
