What molecule forms the cell membrane?

The correct answer will be phospholipids.

Explanation:

Plasma membrane or cell membrane is a thin biological layer surrounding the cytoplasm of the cell separating the interior of the cell from external environment.

The plasma membrane is made up of phospholipids primarily in addition with associated proteins and cholesterol. A phospholipid is a molecule formed of two fatty acid tails, glycerol and a phosphate-linked head group.

It exists as bilayer formed of phospholipids with hydrophobic tails of fatty acids pointing inwards and hydrophilic head facing outwards forming a structure called lipid bilayer.

Thus, phopholipids is the correct answer.