Which of the following bones is considered a long bone?

The femur is classified as a long bone due to its elongated structure and significant length relative to its width. Long bones are characterized by having a shaft, known as the diaphysis, and two ends, called the epiphyses. They primarily function in supporting weight and facilitating movement by serving as levers for muscles. The femur, being the longest bone in the body, plays a crucial role in walking, running, and other physical activities.

In contrast, the carpals are short bones, as they are roughly cube-shaped with equal length and width. Ribs are categorized as flat bones; they have a broad, flat shape that contributes to the thoracic cage structure for protection. The sternum also falls under the category of flat bones, serving as a central structure that articulates with the ribs. Each of these other options possesses distinct characteristics and functions that do not fit the definition of a long bone.