Osmosis enables fluid reabsorption at the venous end Steps:

• Hydrostatic pressure drops from 4.2 kPa at the arterial end to 1.7 kPa at the venous end, reducing outward force.
• Blood plasma proteins create colloid osmotic pressure (about 3.3 kPa), constant along the capillary.
• At the arterial end, hydrostatic pressure exceeds osmotic pressure, causing net filtration out.
• At the venous end, osmotic pressure exceeds hydrostatic pressure, causing net water movement into the blood.

Why D is correct:

• Osmosis is the diffusion of water across a semipermeable membrane from low to high solute concentration, driven here by higher plasma protein concentration pulling water back per Starling's hypothesis.

Why the others are wrong:

• A: Capillary permeability is uniform; pressure gradient, not permeability, controls direction.
• B: Tissue fluid hydrostatic pressure is near zero, lower than blood's 1.7 kPa, favoring inflow.
• C: Plasma has higher solute concentration (proteins) than tissue fluid, driving osmosis inward.

Final answer: D