In the prairie there are many kinds of grasses and other plants that are eaten by grasshoppers and other insects, prairie dogs, and bison. In turn there are many birds that feed on the insects and some hawks that feed on the prairie dogs. The birds use the grasses to build their nests, and bison prefer to feed in areas where prairie dogs have kept the grass short. This is a simplified example of:.
A) an ecosystem.
B) a community.
C) a niche.
D) abiotic factors

What is a difference between systemic and pulmonary circulation? a. systemic circulation carries oxygenated blood to the lungs and pulmonary circulation carries deoxygenated blood to the body. b. systemic circulation carries deoxygenated blood to the lungs and pulmonary circulation carries oxygenated blood to the body. c. systemic circulation carries deoxygenated blood to the body and pulmonary circulation carries oxygenated blood to the lungs. d. systemic circulation carries oxygenated blood to the body and pulmonary circulation carries deoxygenated blood to the lungs.