Which of the following provides the best example of the parts of a system working together to achieve a specific function?
A-Specialized cells in a plant’s leaf open and close in response to changing conditions.
B-Red blood cells are capable of transporting oxygen because of their chemical composition.
C-Glands in the mouth, the stomach, the pancreas, and the small intestine secrete chemicals that break down nutrients.
D-Animals that prey on other animals require the ability to move about in their environment.