Which of the following is a correct statement about an organism and its environment?
a. the gastrovascular cavity provides the nutrient exchange surface in mammals.
b. an animal is a closed system that is separate and distinct from its environment.
c. interstitial fluid is the go-between for body cells and the circulatory system.
d. animals are able to live as long as they remain isolated from their environments. e. none of the choices is correct.

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.