Questions: Provide support, protection, and movement.

The answer is the fourth one: Provide support, protection, and movement.

Explanation for each option:

1. Produce and distribute blood cells.
   This is partially correct. The skeletal system, specifically the bone marrow, is responsible for producing blood cells (a process known as hematopoiesis), but it does not distribute them. Distribution is primarily the function of the circulatory system.

2. Transport oxygen and nutrients throughout the body.
   This is incorrect. The transport of oxygen and nutrients is the primary function of the circulatory system, not the skeletal system.

3. Generate heat and regulate body temperature.
   This is incorrect. Heat generation and temperature regulation are primarily functions of the muscular system and the hypothalamus in the brain, not the skeletal system.

4. Provide support, protection, and movement.
   This is correct. The skeletal system provides the framework that supports the body, protects internal organs, and, in conjunction with the muscular system, facilitates movement.

5. Store and release hormones and other signaling molecules.
   This is incorrect. While bones do store minerals like calcium and phosphorus and can release them into the bloodstream, the storage and release of hormones and signaling molecules are not primary functions of the skeletal system.

In summary, the primary function of the skeletal system is to provide support, protection, and movement.