Among the following compounds nitrobenzene,benzene,aniline and phenol,the strongest basic behaviour in acid medium is exhibited by

Reduction of nitrobenzene with $Zn$ and alcoholic $KOH$ solution results in the formation of the following compound:

In the above conversion of compound $(X)$ to product $(Y)$,the sequence of reagents to be used will be:

Nitrobenzene on reduction by zinc and $NH_4Cl$ gives

Aniline in a set of reactions yielded a product $D$. The structure of product $D$ would be:
Aniline $\xrightarrow{NaNO_2/HCl} A$ $\xrightarrow{CuCN} B$ $\xrightarrow{H_2/Ni} C$ $\xrightarrow{HNO_2} D$

In the given reaction sequence,$Z$ is