Compact bone contains Haversian systems, which run longitudinally within the bone.

The primary site of hematopoiesis in adults is the bone marrow, especially that of the pelvis, cranium, vertebrae, and sternum. The periosteum lines the outer surface of the bone; the endosteum lines its inner surface. The most numerous cell type within compact bone is the osteocyte, not the osteoblast.

Spongy bone is made up of a fine lattice of bone tissue, filled with cavities. Even when these cavities is filled with marrow and other tissue, allowing spongy bone to be light in weight compared to compact bone. The other three statements listed are all true.

The most prolific production sites for red blood cells are the pelvis, cranium, sternum, and vertebrae. Three out of these four sites are flat bones.

Part of the definition of a sesamoid bone is that it is embedded in a tendon. The patella is a classic example. Sesamoid bones are usually short or irregular in shape. They cannot articulate directly with neighboring bones because of the tendons that surround them. They are not commonly broken.

The appendicular skeleton includes the legs and pelvis, which are the normal means of human ambulation. It contains 126 bones as compared to the 80 in the axial skeleton. The primary purpose of the axial skeleton is the protection of vital organs like the heart and lungs. Some bones in the axial skeleton are fused together for stability. The appendicular skeleton requires freedom of movement, which would be restricted by the fusion of its components.

The metaphysis is the portion of bone between the ephiphyses at the ends of a long bone and the long diaphysis in the middle. None of the other bone types have this structure.

Sesamoid bones are those that are formed within tendons and/or muscles, like the patella. They usually act as pulleys, providing a smooth and hard surface over which a tendon may slide. A long bone is a bone that is longer than it is wide. A flat bone forms a thin plate. Finally, a short bone is a bone that tends to be equal in width and length. 

The correct answer is flat bone - most bones in cranium.

Bones can be classified according to shape. There are four classifications of bones: long, short, flat and irregular. Long bones have a long shaft (diaphysis) with two bulky ends (epiphyses), such as bones in the arm, forearm, thigh and leg. Short bones are cubed shaped, such as the bones in the wrist and ankle. Flat bones are thin, flattened and usually curved, such as most bones in the cranium. Bones that do not fit into the flat, long or short categories are irregular bones and include bones in the vertebrae and some bones in the skull.

The correct match between bone and bone types for this question are as follows:

• long bone = bones in forearm
• short bone = bones in wrist
• flat bone = most bones in cranium (correct answer choice)
• irregular bone = bones in vertebrae