Which fluid surrounds body cells and is essential for their function?

The correct choice is the fluid that surrounds body cells and plays a vital role in their function. Extracellular fluid is the general term used to describe all fluid outside of the cells, which includes interstitial fluid that directly bathes the cells. This fluid is essential for a variety of cellular processes, such as nutrient and waste exchange, maintaining osmotic balance, and facilitating communication between cells.

Interstitial fluid, a component of extracellular fluid, surrounds the cells and provides an environment for cell interactions and metabolic activities. The proper balance and composition of extracellular fluid are crucial for homeostasis, enabling cells to function optimally.

Other choices, while related to body fluids, serve different functions. Intercellular fluid typically refers to the fluid within cells, while plasma is the liquid component of blood that transports nutrients and waste but is not the primary fluid that surrounds individual cells. Synovial fluid acts as a lubricant in joints, supporting cartilage and reducing friction, which does not pertain to the fluid directly surrounding body cells.