Which of the following materials is most likely to be radiopaque?

Bone is considered the most radiopaque material among the given options because it has a higher density and atomic number compared to soft tissue, fat, and air. In radiology, radiopacity refers to the ability of a substance to prevent the passage of X-rays, resulting in a lighter appearance on the radiographic film.

Bone contains minerals, primarily calcium, which absorb X-rays more effectively than the other materials listed. This property allows bones to appear white or light gray on radiographs. In contrast, air is radiolucent, meaning it easily allows X-rays to pass through, appearing dark on images. Soft tissue and fat, while denser than air, are still less dense than bone, which is why they appear in various shades of gray on radiographs, but never as white as bone.

Thus, bone's composition and density make it the material most likely to be radiopaque among the choices provided.