Which of the following best describes interstitial water?

Interstitial water refers to the fluid that occupies the spaces between cells and blood vessels in the body's tissues. This fluid plays a critical role in the exchange of nutrients and waste products between blood and cells, facilitating cellular function and hydration. It acts as a medium through which cells receive essential substances and dispose of metabolic waste, making it vital for maintaining homeostasis within the body's internal environment.

The other options describe different compartments of body water. For example, water within cells is specifically called intracellular fluid, while water in the bloodstream is referred to as plasma. Lastly, water surrounding the body is not a standard classification used in the context of body fluid compartments and does not accurately reflect the concept of interstitial water. Understanding interstitial water and its role provides insight into fluid balance and the transport mechanisms critical for proper bodily function.