Which of the following is an example of a flat bone?

The correct answer is the rib, which is classified as a flat bone. Flat bones are characterized by their thin, flattened shape and often serve protective functions for vital organs as well as having a place for muscle attachment. The rib cage, composed of ribs, serves to protect the heart, lungs, and other organs within the thoracic cavity.

In contrast, the humerus is a long bone, which has a tubular structure and is primarily involved in movement and support. The vertebrae are categorized as irregular bones due to their complex shapes that do not fit into the standard categories of long or flat bones. Tarsal bones, which are located in the ankle, are classified as short bones owing to their cube-like structure, providing stability and support for the foot. Thus, the rib is the appropriate example of a flat bone, given its protective role and shape.