Osmosis at Equilibrium Steps:

• The potato's unchanged size indicates no net water gain or loss after 30 minutes.
• This occurs when the external sucrose solution is isotonic to the potato cells.
• Water potential must be equal between the potato and solution for equilibrium.
• At equal water potential, water diffuses in both directions with no net movement.

Why D is correct:

• Water potential equality drives no net osmosis, per the principle that water moves from high to low potential until equilibrium.

Why the others are wrong:

• A: Water concentration equality is imprecise; water potential governs osmosis, and diffusion continues bidirectionally.
• B: Focuses on water concentration, not potential; omits no net outflow.
• C: Ignores bidirectional diffusion; net movement is zero, not absolute absence into the potato.

Final answer: D