* Heterogeneous mixtures have components that are not evenly distributed and can be visually distinguished.

* Dusty air contains particles of dust, which are solid materials suspended in the air. These dust particles are not evenly distributed and can be seen as specks or haze.

Let's look at the other options:

* Elements are pure substances made up of only one type of atom (e.g., oxygen, gold).

* Compounds are pure substances made up of two or more different elements chemically combined (e.g., water, carbon dioxide).

* Homogeneous mixtures have components that are evenly distributed and cannot be visually distinguished (e.g., saltwater, air without dust).

Since dusty air has visible, unevenly distributed components, it fits the definition of a heterogeneous mixture.