The fluid mosaic model shown above describes the structure and function of a. nuclei. b. cell membranes. c. chloroplasts. d. chromosomes.

             The corrrect option is B (Cell membrane). 

Explanation:
                   Fluid Mosaic Model was proposed by Fluid Mosaic Singer and GL Nicolson in 1972, to describe the structure of cell membrane. 

Statement:
                  "According to this model cell membrane is like a sea of lipids in                                       which protein molecules are floating".

Explanation:
                     Fluid mosaic model show that cell membrane is composed of:

1. proteins:
                    Two types of proteins are present in cell membrane.

a. Intrinsic protein:
                               Also known as integral proteins. These proteins are nestled into phospholipid and embedded in the cell membrane. 

b. Extrinsic protein:
                                 These proteins are also known as peripheral proteins. These are present on the surface of cell membrane. 

2. Phospholipid:
                            Each phospholipid is composed of head and two tails. The head is phosphate group which is hydrophilic while tail is composed of fatty acid which is hydrophobic. 

3. Carbohydrate molecules:
                                             It is the third major composition of plasma membrane. Two types of conjugating molecules are also present in plasma membrane.

Example:
                Glycolipids and glycoproteins.

4. Cholesterol:
                        Cholesterol is a type of steroid which help in regulating molecule entering and exiting cell.