The set that represents the pair of neutral oxides of nitrogen is :

$\mathrm{NO}$ and $\mathrm{N}_{2} \mathrm{O}$

$\mathrm{N}_{2} \mathrm{O}$ and $\mathrm{N}_{2} \mathrm{O}_{3}$

$\mathrm{N}_{2} \mathrm{O}$ and $\mathrm{NO}_{2}$

$\mathrm{NO}$ and $\mathrm{NO}_{2}$