Final answer:
The major organic component of bone extracellular matrix is collagen (option a), which provides a surface for hydroxyapatite crystals, ensuring bones are strong yet flexible.
Step-by-step explanation:
The major organic component of bone extracellular matrix is collagen. Bone is the hardest connective tissue, providing protection to internal organs and support for the body. Its rigid extracellular matrix comprises mostly collagen fibers, which are essential for the structural integrity of bone. These fibers provide a surface for inorganic hydroxyapatite crystals to adhere, a mineral formed from calcium phosphate.
The hydroxyapatite gives bones their hardness and strength, while the collagen fibers lend flexibility and prevent brittleness. The organic matrix also includes osteoblasts, which are responsible for the deposition of new bone matrix and subsequent mineralization of collagen with hydroxyapatite during bone formation.