Stores minerals and forms blood cells within bones.

• A. Skeletal system
• B. Muscular system
• C. Cardiovascular system
• D. Endocrine system

Answer: (A)

Bones act as a mineral reservoir and the site of blood cell formation. The mineral content, especially calcium and phosphate, is stored in the bone matrix and can be released into the bloodstream to help regulate mineral balance and vital bodily functions. Inside red bone marrow, hematopoiesis produces red blood cells, white blood cells, and platelets, so bones are directly involved in forming the body's blood cells. Some marrow becomes yellow marrow with fat storage as people age, but the essential idea remains: the skeletal system stores minerals and supports blood cell production. Other systems handle movement, circulation, or hormonal regulation, but they do not provide this combination of mineral storage and blood cell formation within bone.