Answer the following question given this paragraph: 

Photochemical smog consists mainly of ozone (O 3 ). The ozone in smog is the same compound as the ozone in the ozone layer,(O 3 ). But ozone in smog is found near the ground. Figure below shows how it forms. When nitrogen oxides and VOCs are heated by the Sun, they lose oxygen atoms. The oxygen atoms combine with molecules of oxygen to form ozone. Smog ozone is harmful to humans and other living things.


Q: What dangerous oxygen compound is found in ground level smog?

 Choices:

- argon

- sulfur dioxide

- neon

- ozone

A:
ozone
