Which one of the following oxides of nitrogen is a greenhouse gas?

Nitrous oxide is a long-lived greenhouse gas that traps heat far more strongly than carbon dioxide.

Nitrogen dioxide is a reactive pollutant tied to smog rather than a greenhouse gas.

Nitric oxide is a short-lived reactive gas, not a greenhouse gas.

Dinitrogen trioxide is unstable and is not counted among greenhouse gases.

The stable oxide that persists and warms the atmosphere is the one that counts.

Nitrous oxide comes largely from fertilised soils and agriculture.