Diffusion rate depends on surface area and temperature

Steps:

• Identify key factors: Diffusion rate is proportional to surface area (larger area allows more molecules to cross) and increases with temperature (higher kinetic energy speeds molecular movement).
• Evaluate surface area: Large area maximizes diffusion compared to small area.
• Evaluate temperature: High temperature accelerates diffusion more than low temperature.
• Combine for fastest rate: Large surface area with high temperature yields the maximum rate.

Why D is correct:

• It pairs large surface area (increases rate per Fick's law: rate ∝ area) with high temperature (increases molecular speed and permeability).

Why the others are wrong:

• A: Small area and low temperature both slow diffusion.
• B: Small area limits diffusion despite high temperature.
• C: Low temperature slows diffusion despite large area.

Final answer: D