Explanation:

- Ozone is a molecule composed of three oxygen atoms. This is the correct statement and represents the chemical formula \( O_3 \).

- Option:4, three is the correct choice.

- Option:1, four is incorrect. Oxygen molecules typically do not form stable structures with four atoms.

- Option:2, two refers to diatomic oxygen (\( O_2 \)), which is the most common form of oxygen in the atmosphere.

- Option:3, one describes atomic oxygen, which is highly reactive and not stable alone in nature.