Which of the following is a connective tissue?

• A. Smooth muscle
• B. Nervous tissue
• C. Epithelium
• D. Cartilage

Answer: (D)

Connective tissue is defined by cells embedded in an extracellular matrix that provides structure and support. Cartilage fits this pattern because it contains chondrocytes housed in lacunae within a firm, gel-like matrix made mainly of collagen fibers and proteoglycans. This matrix gives cartilage its sturdy yet flexible support, cushions joints, and helps shape structures like the ears and nose. It is typically avascular, relying on diffusion for nutrients, which is another characteristic of many connective tissues.

By contrast, smooth muscle is specialized for contraction, nervous tissue for transmitting electrical signals, and epithelium lines surfaces and forms glands. The presence of an extracellular matrix with embedded cells distinguishes cartilage as a connective tissue.