Biology

The correct answer is: B.A double layer of phospholipids

The cell membrane is primarily made up of a phospholipid bilayer, which consists of two layers of phospholipids. The hydrophobic (water-repelling) tails face inward, away from water, while the hydrophilic (water-attracting) heads face outward, towards the water inside and outside the cell. This arrangement forms a flexible, semi-permeable barrier that regulates what enters and exits the cell.

The other options are not correct:

A.A rigid layer of proteins: Proteins are embedded within...