Final answer:
Bone is primarily made up of A) calcium in the form of calcium phosphate and calcium carbonate, which combine to create hydroxyapatite. This gives bones their strength while collagen fibers provide flexibility.
Step-by-step explanation:
Bone is composed primarily of calcium as an inorganic material. This calcium is present in the form of calcium phosphate and calcium carbonate which combine to create hydroxyapatite. This substance crystallizes on a matrix of collagen fibres, providing bones with their notable hardness and strength, while collagen gives the bones flexibility to avoid brittleness. Magnesium, fluoride, and sulfate are incorporated into the hydroxyapatite as it forms, playing a supportive role in bone health, but calcium is the main inorganic component of bone tissue.