The heart's pumping action generates hydrostatic pressure in the blood. The table gives the hydrostatic pressure in a blood capillary. Arteriole end of capillary: $4.2\ \text{kPa}$ Venule end of capillary: $1.7\ \text{kPa}$ Approximately $90\%$ of the tissue fluid that surrounds a capillary is returned to the blood at the venule end. By what means is this brought about?
- AThe capillary wall is more permeable at the arteriole end than the venule end.
- BThe hydrostatic pressure in tissue fluid is higher than in blood.
- CThere is a higher concentration of dissolved solutes in tissue fluid than in blood.
- DThere is osmotic movement of water from the tissue fluid into the blood.