A sodium salt X decolourises acidified $\mathrm{KMnO}{}_4$, gives a brown vapour at the mouth of the tube with dilute $\mathrm{H}{}_2\mathrm{SO}{}_4$ and turns starch-iodide paper blue after acidification. X, the oxidation state of nitrogen in the product of oxidation by $\mathrm{KMnO}{}_4$, and the moles of $\mathrm{MnO}{}_4{}^{-}$ consumed per mole of X are respectively

1. A$\mathrm{NaNO}{}_2$ ; +4 ; 0.4
2. B$\mathrm{NaNO}{}_2$ ; +5 ; 0.4
3. C$\mathrm{NaNO}{}_2$ ; +5 ; 2.5
4. D$\mathrm{NaNO}{}_2$ ; +3 ; 0.4