Cell is the basic structural unit of the body. Membrane is a structural component that separates intracellular and extracellular environment by means of plasma membrane.
Fluid mosaic model describes that two-dimensional liquid layer of plasma membrane where proteins distributed like mosaic model in the phospholipid bilayer. This model mostly accepted by biologists Role of the protein molecules in this model cell membrane layers are membrane extracellular protein domains in connection to the lipid bilayer membrane.
Membrane phospholipids are the molecules with hydrophillic polar heads towards the solvent such as water whereas hydrophobic tail located towards the center of the layer and this bilayer formed by micelles, as fatty acids possess one polar associated with another nonpolar head. These phospholipids are integral components of plasma membrane. Biological lipid bilayers are composed of phospholipids to form spontaneously into bilayers because the hydrophobic tails, which associate as "amphiphilic phospholipids" with hydrophilic phosphate head. Phospholipids ate not integral components of mitochondrial membrane.
Thus, the options (a), (c) and (b) are incorrect.
Membrane phospholipids are the molecules with hydrophillic polar heads towards the solvent such as water whereas hydrophobic tail located towards the center of the layer and this bilayer formed by micelles, as fatty acids possess one polar associated with another nonpolar head. These phospholipids are considered as integral components of plasma membrane.
Therefore, the correct option is – d. they are integral components of the plasma membrane.