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.

Interstitial fluid is an extracellular fluid that fills the spaces between most of the cells of the body ("bathes the cells").

The total body water is divided between the intracellular compartment (intracellular fluid) and the extracellular compartment (extracellular fluid). Extracellular fluid is then subdivided into interstitial fluid and smaller components, such as the blood plasma, the cerebrospinal fluid and lymph.

Interstitial fluid consists of a water solvent which contains sugars, salts, fatty acids, amino acids, coenzymes, hormones, neurotransmitters, white blood cells and cell waste products. The composition of interstitial fluid is not always the same, it depends upon the exchanges between the cells in the biological tissue and the blood (different composition of the fluid in different tissues). The interstitial fluid acts as a connecting link between the blood and the cells.

The statement that is correct about an organism and its environment is intrinsitial fluid is the go-between for body cells and the circulatory system.