The major interaction responsible for stabilizing plasma membrane

The correct option is hydrophobic interactions.

To understand why hydrophobic interactions are the major force stabilizing the plasma membrane, let us break down the structure of the membrane and the thermodynamic forces at play:

1. Structure of the Lipid Bilayer:
The plasma membrane is primarily composed of a bilayer of phospholipids. Each phospholipid molecule is amphipathic, meaning it has two distinct regions:
- A polar, hydrophilic (water-loving) head group.
- Two non-polar, hydrophobic (water-fearing) fatty acid tails.

2. The Role of Water and the Hydrophobic Effect:
The intracellular and extracellular environments are aqueous (water-based). When amphipathic lipid molecules are placed in water, water molecules form a highly ordered "cage" or clathrate structure around the non-polar hydrophobic tails to maximize hydrogen bonding among themselves. This organization represents a decrease in entropy, which is thermodynamically unfavorable.

3. Stabilization through Hydrophobic Interactions:
To minimize this decrease in entropy, the hydrophobic tails aggregate together, shielding themselves from water. This clustering releases the ordered water molecules back into the bulk solution, increasing the entropy of the system (a thermodynamically favorable process where free energy change $\Delta G<0$). The non-covalent association that results from this exclusion of water is called a hydrophobic interaction.

4. Summary of Membrane Stability:
While hydrogen bonding and electrostatic (hydrophilic) interactions occur between the polar head groups and water, and weak van der Waals forces exist between the packed hydrocarbon tails, it is the hydrophobic effect (hydrophobic interactions) that drives the spontaneous assembly and provides the primary thermodynamic stabilization of the lipid bilayer structure of the plasma membrane.