Answer:
Phospholipid layer
Step-by-step explanation:
The plasma or cell membrane is the outer covering of prokaryotic (bacteria) and eukaryotic (plants and animal) cells that provides support to the cytoplasm. The plasma membrane is made up of components like phospholipid layer, proteins, etc. However, the PHOSPHOLIPID LAYER component of the plasma membrane confers its SEMI-PERMEABILITY upon it.
The phospholipid layer consists of a hydrophilic i.e. water-loving region (phosphate head) and hydrophobic i.e. water-fearing region (fatty acid tails) that allows it to selectively control the flow of molecules into and out of the cell.