Someone help pleaseee easy 7th grade work
which of the following provides the best examples 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 enviroment