${\mathrm{CH}}_2\mathrm{Br}-{\mathrm{CH}}_2\mathrm{Br}$  $\stackrel{\mathrm{alcoholic} \mathrm{KOH}}{\to }\mathrm{X}$

$\mathrm{X}+{\mathrm{NaNH}}_2$ $\stackrel{\mathrm{Heat}}{\to }$ Acetylene

Here $\mathrm{X}$ is 

${\mathrm{CH}}_2\mathrm{Br}-{\mathrm{CH}}_2\mathrm{Br}$ $\stackrel{ \mathrm{alcoholic} \mathrm{KOH}}{\to }{\mathrm{H}}_2\mathrm{C}=\mathrm{CHBr}$

${\mathrm{H}}_2\mathrm{C}=\mathrm{CHBr}+{\mathrm{NaNH}}_2$ $\stackrel{\mathrm{Heat}}{\to }\mathrm{HC}\equiv \mathrm{CH}+\mathrm{NaBr}+{\mathrm{NH}}_3$

Hence, X is vinyl bromide.

Therefore, option (A) is correct.