(A) is the right answer.
Chondroitin is a molecule that occurs naturally in the body. It is a major component of cartilage -- the tough, connective tissue that cushions the joints. Commercial chondroitin is derived from natural sources, such as shark and bovine cartilage, or synthetic production. Chondroitin helps keep cartilage healthy by absorbing fluid (particularly water) into the connective tissue. It may also block enzymes that break down cartilage, and it provides the building blocks for the body to produce new cartilage.