Conversion of benzene diazonium chloride to chlorobenzene is an example of which of the following reactions?

Industrially,chlorobenzene is prepared by:

Chlorobenzene is prepared commercially by

Fluorobenzene $(C_6H_5F)$ can be synthesized in the laboratory

$C_6H_5Cl$ is prepared from aniline by:

In Gattermann reaction,a diazonium group is replaced by $\underline{X}$ using $\underline{Y}$. $\underline{X}$ and $\underline{Y}$ are:
$\underline{X} \quad \underline{Y}$