Match the reactants in Column-$I$ with the products in Column-$II$.

Column-$I$ (Reactants)	Column-$II$ (Products)
$(A) CH_3CH_2Br + Mg \xrightarrow{\text{dry ether}}$	$(i) \text{Cyclohexylmagnesium bromide}$
$(B) 2RX + 2Na \xrightarrow{\text{dry ether}}$	$(ii) CH_3CH_2MgBr$
$(C) CH_3CH_2Br \xrightarrow{\text{alc. KOH}}$	$(iii) R-R + 2NaX$
$(D) \text{Bromocyclohexane} + Mg \xrightarrow{\text{dry ether}}$	$(iv) CH_2=CH_2 + H_2O + KBr$

(A-II, B-III, C-IV, D-I) $(A) CH_3CH_2Br + Mg \xrightarrow{\text{dry ether}} CH_3CH_2MgBr$ (Grignard reagent formation),so $(A \rightarrow ii)$.
$(B) 2RX + 2Na \xrightarrow{\text{dry ether}} R-R + 2NaX$ (Wurtz reaction),so $(B \rightarrow iii)$.
$(C) CH_3CH_2Br \xrightarrow{\text{alc. KOH}} CH_2=CH_2 + H_2O + KBr$ (Dehydrohalogenation),so $(C \rightarrow iv)$.
$(D) \text{Bromocyclohexane} + Mg \xrightarrow{\text{dry ether}} \text{Cyclohexylmagnesium bromide}$ (Grignard reagent formation),so $(D \rightarrow i)$.
Therefore,the correct matching is $(A$ $\rightarrow ii, B$ $\rightarrow iii, C$ $\rightarrow iv, D$ $\rightarrow i)$.