Explanation:
Cartilage is a type of connective tissue, while areolar tissue is another type of connective tissue. They are distinct and have different characteristics, so matching cartilage with areolar tissue is a wrong pairing.

Connective Tissue:
Connective tissue is one of the four main types of tissue in the human body. It is responsible for providing support, structure, and protection. Connective tissue is made up of cells and an extracellular matrix that consists of fibers and ground substance.

Cartilage:
Cartilage is a type of connective tissue that is flexible and found in various parts of the body. It is composed of cells called chondrocytes, which are embedded in an extracellular matrix. Cartilage provides support, cushioning, and flexibility to different structures such as the joints, nose, and ears.

Areolar Tissue:
Areolar tissue is another type of connective tissue that is widely distributed throughout the body. It is composed of various cell types such as fibroblasts, macrophages, and mast cells. Areolar tissue is characterized by its loose arrangement of collagen and elastic fibers, as well as its abundance of ground substance. It provides support, elasticity, and strength to surrounding structures.

Wrong Pairing:
Matching cartilage with areolar tissue is incorrect because they have different structures and functions:

- Cartilage is a specialized connective tissue that is characterized by its firmness and flexibility.
- Areolar tissue is a loose connective tissue that is characterized by its loose arrangement of fibers and cells.

Correct Pairing:
The other options provided are correct pairings:

- Unicellular glandular cells are specialized cells that produce and secrete substances. Goblet cells are a type of unicellular glandular cell that secretes mucus.
- Saliva is an exocrine secretion, which means it is produced by glands and released through ducts.
- Fusiform fibers are found in smooth muscle, which is a type of muscle tissue responsible for involuntary movements in organs such as the digestive system.

Therefore, the correct answer is option D, as cartilage and areolar tissue are not correctly matched.