$\mathrm{R}-{\mathrm{NO}}_2\stackrel{\mathrm{X}}{\to }\mathrm{R}-{\mathrm{NH}}_2;$ ‘X’ in this reaction can be

$\mathrm{A}) {\mathrm{H}}_2/\mathrm{Pt} \mathrm{B}) {\mathrm{LiAlH}}_4 \mathrm{C}) \mathrm{Sn}/\mathrm{HCl} \mathrm{D})\hspace{0.17em}\mathrm{Zn}/\mathrm{HCl}$

$\mathrm{R}-{\mathrm{NO}}_2$ can be reduced  to $\mathrm{R}-{\mathrm{NH}}_2$ by catalytic reduction $\left({\mathrm{H}}_2/\mathrm{cat}\right)$ ,acidic reduction (metal/acid) (or) by using ${\mathrm{LiAlH}}_4$