Answer:
The correct answer would be B. cell membranes.
Fluid mosaic model is one of the models which explains the structure of functional cell membrane.
It explains cell membrane as the mosaic structure made up of components like phospholipid, proteins, cholesterol, and carbohydrates which provide the cell membrane a fluid nature.
Phospholipids are the prime component of the lipid bilayer. Proteins are embedded in the lipid bilayer structure and serve different functions like cell signaling.