which statement must be mentioned in explaining why amphipathic molecules line up at a water surface?

The key statement to explain why amphipathic molecules line up at a water surface is that polar water molecules pull together, holding the polar (hydrophilic) parts of the amphipathic molecules and squeezing out the nonpolar (hydrophobic) parts. This means that the hydrophilic heads interact with the water molecules while the hydrophobic tails avoid water and cluster away from the surface. This dual affinity causes the amphipathic molecules to arrange themselves at the water surface with their hydrophilic heads in the water and hydrophobic tails sticking out or away from the water.