Which statement is true about osmotic pressure?

Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane due to solute concentration differences. The correct answer highlights that osmotic pressure must indeed be countered by hydrostatic pressure within a system.

In contexts such as capillary circulation, osmotic pressure works to pull water into the bloodstream, helping to maintain the balance of fluids between compartments. Hydrostatic pressure, which is the pressure exerted by a fluid, acts in the opposite direction and influences fluid movement out of the capillaries into the surrounding tissues. Therefore, for equilibrium to be maintained, hydrostatic pressure must counterbalance osmotic pressure. This is a fundamental principle in understanding fluid dynamics in the body, particularly in the circulatory system and in kidney function.

Overall, recognizing the interplay between osmotic and hydrostatic pressures is crucial for understanding how fluids move in and out of cells and blood vessels, impacting physiological processes like nutrient delivery and waste removal.