Most impoant factor for maintaining intravascular fluid volume -

Ans. is 'b' i.e., Osmotic pressure in capillaries[Ref: Understanding medical physiology p. 331)Hydrostatic pressure in the capillaries, i.e., capillary blood pressure creates an outward driving force i.e., tries to force the fluid from the capillary to interstitial space.Osmotic pressure in the capillaries creates an inward driving force, ie., tries to keep the fluid in the capillary.