Which of the following is not a function of the skeletal system?
a. Primary storage site in the body for sodium and potassium salts      
b. Location of the red bone marrow, which produces red blood cells 
c. Storage of triglycerides in yellow bone marrow    
d. Support and protection of the body and vital organs

The skeletal system serves several critical functions, including providing structural support to the body, protecting vital organs, facilitating movement through attachment points for muscles, and serving as a reservoir for minerals such as calcium and phosphorus. Additionally, it plays a role in hematopoiesis, the production of blood cells, within the bone marrow.

Bone marrow is classified into two types: red bone marrow and yellow bone marrow. Red bone marrow is primarily responsible for the production of red blood cells, white blood cells, and platelets, while yellow bone marrow serves as a storage site for fats (triglycerides) and can convert to red marrow in response to increased demand for blood cell production.

Bones act as a major storage site for essential minerals, particularly calcium and phosphorus, which are vital for various bodily functions, including nerve transmission and muscle contraction. The skeletal system also stores sodium and potassium salts, although their primary storage occurs in other tissues, making this function less emphasized in the context of the skeletal system.