In the following reaction, B is

$\mathrm{A}\stackrel{\mathrm{Bromination}}{\to }\mathrm{B}\stackrel{{\mathrm{NaNO}}_2/\mathrm{HCl}}{\to }\mathrm{C}\stackrel{\mathrm{Boiling}}{\underset{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}}{\to }}\mathrm{sym}-\mathrm{tribromobenzene}$

In the following reaction, 

Compound $\left(\mathrm{A}\right)$ and $\left(\mathrm{B}\right)$ respectively are:-

Which of the following chemicals are used to manufacture methyl isocyanate that caused "Bhopal Tragedy"?

$\left(\mathrm{i}\right)$ Methylamine.
$\left(\mathrm{ii}\right)$ Phosgene.
$\left(\mathrm{iii}\right)$ Phosphine.
$\left(\mathrm{iv}\right)$ Dimethylamine.

In the reaction,

${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NH}}_2\frac{{\mathrm{NaNO}}_2/{\mathrm{HBF}}_4}{273 \mathrm{K}}\left(\mathrm{A}\right)\stackrel{\mathrm{\Delta }}{⟶}{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{F}$, the compound $\left(\mathrm{A}\right)$ is known as:

The final product $\mathrm{C}$ obtained in this reaction,

woluld be: