Answer:
external fertilization
Explanation:
External fertilization cannot happen on land since it needs a medium for the fertilization to be able to take place, but land cannot provide the medium.
Hope it helps.
By definition: Facilitated diffusion<span> is the process of spontaneous passive transport of molecules or ions across a cell's membrane via specific transmembrane integral proteins.~Google
An example, the only I can really think of:
Polar and large molecules normally can't cross the lipid bi layer using simple diffusion, it usually has to be </span>Facilitated diffusion
