Answer:
The correct answer is hydrophobic tails of lipid bilayer forming cell membrane.
Step-by-step explanation:
Plasma membrane is the specialized structure which forms the outer boundary of the cell and controls the entry and exit of substances into the cell thus, determining the nature of its contact with environment.
The cell membrane structure consists of amphipathic phospholipids with two components arranged in a manner:
1. Hydrophilic "head" region- made of phosphate molecule interacting with aqueous side or the intracellular (cytosolic) and extracellular faces
2. Hydrophobic "tail" regions- made of fatty acid chains away from the surrounding water.
This, results in the formation of lipid bilayer.
Thus, the hydrophobic tails of lipid bilayer prevents water from entering the cell.