Which one of the following methods is neither meant for the synthesis nor for separation of amines?

$C_3H_9N$ represents

Identify the product $B$ in the following reaction:
$C_6H_5NH_2$ $\xrightarrow[0^\circ-5^\circ C]{NaNO_2/HCl} A$ $\xrightarrow{Ph-N(CH_3)_2} B$

Ethylamine can be obtained by the:

Convert:
$(i)$ $3-$Methylaniline into $3-$nitrotoluene.
$(ii)$ Aniline into $1,3,5-$tribromobenzene.

Amongst the compounds given,the one that would form a brilliant colored dye on treatment with $NaNO_2$ in dil. $HCl$ followed by addition to an alkaline solution of $\beta$-naphthol is