• this is dehydrohalogenation of cyclohexyl bromide which involves removal of (elimination of) a hydrogen halide ..

• Alcoholic KOH forms hydroxide ions act as a strong nucleophile and replaces the halogen atom from cyclohexyl halide which later leads to formation of cyclohexene.

• For option (i) this reaction is preparation of alkyl amines from an alkyl halide treating with ammonia.

Other 2 options (i) and (iv ) are not possible.