Which of the following correctly provides an example of the hierarchical structure of living organisms?
A.
Organisms that live in the ocean, as opposed to on land, have developed different ways to obtain oxygen.
B.
Human blood cells are specialized to transfer oxygen throughout the body.
C.
The digestive system of animals is made up of organs that work together to break down food.
D.
Reptiles and amphibians have a shared ancestry, so many of their body structures are similar.
