Assertion: Water transport across biological membranes is too specific and too rapid to be explained entirely by diffusion through the lipid layer.
Reason: Water molecules are so small that they move relatively freely across the lipid bilayer, even though the middle zone is hydrophobic.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.