Non-polar molecules enter cells via ATP-independent passive diffusion

Steps:

• Identify molecule X as non-polar based on diagram showing direct membrane crossing without carriers.
• Non-polar molecules dissolve in lipid bilayer for simple diffusion.
• Simple diffusion is passive, driven by concentration gradient only.
• ATP powers active transport, irrelevant for passive processes.

Why D is correct:

• Non-polar molecules enter via simple diffusion, defined as ATP-independent passive movement across lipid bilayers.

Why the others are wrong:

• A: Non-polar entry unaffected by ATP, so "affects rate" is incorrect.
• B: Polar molecules often require ATP-dependent active transport, so "no effect" is incorrect.
• C: Molecule X is non-polar, not polar.

Final answer: D