The basic unit of the cell membrane is Phospholipid.
Option (d);
EXPLANATION:
The cells are smaller in size forms the basic unit or part in living organisms.Each cell has a cell membrane that covers the cell and keeps all the contents inside. The structure of this cell membrane is mainly classified into two layers of lipids or fats altogether called Phospholipids.Cell membrane is also called Plasma membrane. Phospholipids have a hydrophilic head, that can dissolve in water and a hydrophobic tail, that cannot be dissolved in water.