Which mineral is primarily stored in bone and is essential for bone strength?

• A. Phosphorus
• B. Calcium
• C. Iron
• D. Potassium

Answer: (B)

Bones store minerals to give them strength, and calcium is the central mineral for this purpose. Calcium combines with phosphate to form hydroxyapatite crystals, which fill the bone matrix and give bones their hardness and rigidity. This mineral also serves as a reservoir: when blood calcium is low, calcium is released from bone to support essential functions like muscle contraction and nerve signaling. Phosphorus is important too, but its role in bone strength is tied to its association with calcium in those crystals. Iron and potassium are needed elsewhere in the body and do not provide the primary structural strength that calcium does in bone.