Which structural arrangement of phospholipids is most energetically favored in an aqueous environment and why?

• A. Linear single-file chains oriented across the water column, because this maximizes hydrophobic exposure to water and therefore reduces entropy loss.
• B. Bilayer formation with hydrophilic heads facing the aqueous exterior and interior and hydrophobic tails sequestered inside, because this arrangement minimizes unfavorable water–hydrophobic tail interactions while maintaining headgroup hydration.
• C. Randomly dispersed monomers uniformly mixed with water, because amphipathic molecules have no tendency to self-assemble and will remain in monomeric form under physiological conditions.
• D. Crystalline lattice of phospholipids with tails protruding into the water and heads buried internally, because burying polar groups reduces energetic cost in an aqueous environment.

Answer: (B)