What is the major component of extracellular fluid?

The major component of extracellular fluid is indeed extracellular fluid itself, which includes all the fluid outside of cells. It encompasses several subcategories, including interstitial fluid (the fluid that bathes the cells) and plasma (the liquid component of blood). The primary role of extracellular fluid is to provide a medium for the exchange of nutrients, waste materials, and other substances between blood and cells, facilitating various physiological processes necessary for maintaining homeostasis.

In this context, while interstitial fluid is a significant part of the extracellular fluid, it is not the entirety of it. Intracellular fluid refers to the fluid inside the cells, and cytoplasm is the material within the cell membrane, excluding the nucleus. Therefore, the answer correctly identifies extracellular fluid as the overarching category that includes all components externally located to the cells.