Which statement describes the characteristics of long bones?

• A. They are short, cube-shaped bones commonly found in wrists and ankles.
• B. They are primarily made of spongy bone with little compact bone.
• C. They lack a diaphysis and medullary cavity.
• D. They are longer than they are wide, with a shaft and two ends.

Answer: (D)

Long bones are defined by their elongated shape, being longer than they are wide, and they have a central shaft called the diaphysis with two ends known as the epiphyses. The shaft typically consists of dense compact bone that provides strength, and it encloses a hollow medullary cavity that houses bone marrow. The ends are broader and contain more spongy (trabecular) bone, often supporting red marrow involved in blood cell production. This configuration—a bone that is long with a shaft and two ends—best matches the description. The other statements describe short, cube-shaped bones, mischaracterize the bone's outer composition, or claim there is no diaphysis or medullary cavity, which doesn’t fit long bones.