Identify the compound from the following having the highest basic strength.

Identify compound $X$ in the following reaction.

The final product $[B]$ is :

Identify what is $Y$ in the following reaction sequence?
$CH_3CONH_2$ $\xrightarrow{Br_2/NaOH(aq)} X$ $\xrightarrow[(ii) H_2O]{(i) NaNO_2 + HCl} Y$

The action of nitrous acid with ethylamine produces:

Consider the following:
$(I)$ $CH_3CH_2NH_2$
$(II)$ $PhCH_2NH_2$
$(III)$ $PhNH_2$
The correct order of their basic strength is: