Final answer:
Blood cell production is not a primary function of the skeletal system; the primary functions are support, movement, and protection of internal organs, as well as the storage of minerals and fats.
Step-by-step explanation:
The function that is NOT a primary function of the skeletal system is blood cell production. The primary functions of the skeletal system include support, movement, and protection of internal organs. It also stores and releases minerals and fat. The bones are crucial for maintaining our structure and facilitating movement.
They protect vital organs such as the brain, heart, and lungs. The bones are also the main storage sites for minerals like calcium and phosphate and store fat in the yellow marrow. However, while bones do house the bone marrow where blood cell formation occurs, the actual production of blood cells is considered a secondary function, not a primary one, as it is not related to the structural or mechanical roles of the skeletal system.