In a plasma membrane how do the tails of the phospholipid molecules line up?

To the formation of plasma membrane, phospholipid molecules are line up next to each other with their tails (hydrophobic in nature) inside of the cell and head (hydrophilic in nature) on the outside. While the tail facing off to the cell and head facing inside the cell the second layer of phospholipids formation will occur.

In this position a formation of double layer is occurred with head along with phosphate group facing outside and tail along with fatty acid inside the cell. This double layer is known as lipid bilayer which forms the main part of the plasma membrane.

Phosphate group which is present on the bilayer is composed of phosphorus molecule with 4 oxygen molecules and long chain of fatty acids are composed of hydrogen and carbon, these 2 molecules are connected to each other with the help of glycerol.

answer: b

coz red blood cells marrow and circulates the body for 120 days.