Give the structure of $A$ in the following reaction.
$2\text{-Nitro-4-methylaniline} \xrightarrow[(ii) \ H_3PO_2, H_2O]{(i) NaNO_2 + HCl, 273 - 278 \ K} A$.

(A) The reaction proceeds in two steps:
$1$. Diazotization: $2\text{-Nitro-4-methylaniline}$ reacts with $NaNO_2 + HCl$ at $273-278 \ K$ to form the diazonium salt,$2\text{-nitro-4-methylbenzenediazonium chloride}$.
$2$. Deamination: The diazonium salt is then treated with $H_3PO_2$ and $H_2O$,which reduces the diazonium group to a hydrogen atom,resulting in $3\text{-methylnitrobenzene}$ (also known as $m\text{-nitrotoluene}$) as the final product $A$.