The correct option is D Perichondrium Cartilage is a strong, flexible and semi-rigid supporting tissue. It can withstand compression forces, and yet it can bend. It is made up of cells called chondroblasts and chondrocytes, (chondro - cartilage) and extracellular matrix, made up about 10% aggrecan, 75% water, and a mix of collagen fibres and other constituents. The surface of most cartilage is covered by a layer of dense irregular connective tissue called the perichondrium (peri = around). The outer layer of the perichondrium contains collagen-producing fibroblasts, and the inner layer contains chondroblasts.