The interstitial fluid is called the internal environment of the body because: a) Proper functioning of body cells depends upon the precise regulation of the fluid surrounding them. b) Proper functioning of body cells depends upon the precise regulation of the fluid within them. c) All interstitial fluid has the same composition. d) a and b are correct

a) Proper functioning of body cells depends upon the precise regulation of the fluid surrounding them

Explanation:

Interstitial fluid comes out of blood vessels and it is present between the cell spaces. It surrounds and bath the cells. It is the major ECF fluid in the body. Interstitial fluid carry the nutrients to the cell for their proper functioning. After providing the nutrient it collects the waste material from cell and known as lymph. Lymph drains into circulation of cardiovascular system.