The fluid mosaic model describes the mosaic nature of the cell membrane. Fluid mosaic modal signifies that the plasma membrane is made up of lipid bilayer which is not fully rigid and gives fluidity to its membrane.
Due to this fluidity, components of the plasma membrane, like various plasma membrane proteins move freely in the membranes. This elasticity of the plasma membrane allows some proteins to do flip-flop movement.
These movements of plasma membrane components play important role in the cell signaling and transport of molecules across the cell. Therefore the correct answer is B.cell membrane.
