Amongst the following greenhouse gases (GHGs), whose Global Warming Potential (GWP) is considered as 1?

Carbon dioxide is assigned a global warming potential of one, serving as the reference gas.

Chlorofluorocarbons have global warming potentials in the thousands, far above one.

Nitrous oxide has a potential of a few hundred, not one.

Methane has a potential of around twenty five to thirty over a century, not one.

All other greenhouse gases are rated by comparing their heat trapping to that of carbon dioxide.

Carbon dioxide dominates warming mainly through its sheer atmospheric abundance and long lifetime.