Irregular bones include vertebrae and facial bones.

• A. Carpals and tarsals
• B. Ribs
• C. Vertebrae and facial bones
• D. Clavicles

Answer: (C)

Irregular bones are those with complex, non-uniform shapes that don’t fit the categories of long, short, or flat. This irregularity suits their specialized roles. Vertebrae exemplify this, with blocky bodies and various processes that interlock with adjacent vertebrae, provide points for ligaments and muscles, and help protect the spinal cord. Facial bones also fall into this group because they have intricate forms to create the shape of the face, form the eye sockets and nasal passages, and provide multiple surfaces for muscle and ligament attachment.

In contrast, short bones like the carpals and tarsals are cube-like and compact; ribs are flat bones with broad surfaces for protection and extensive muscle attachments; and the clavicle is a long bone that functions as a supportive strut for the shoulder. These shapes align with their primary roles and aren’t irregular. So, vertebrae and facial bones are the irregular ones.