Butanedioic acid can be prepared from 1,2-dibromoethane in two stages. $\text{BrCH}_2\text{CH}_2\text{Br} \xrightarrow{\text{step 1}} X \xrightarrow{\text{step 2}} \text{HO}_2\text{CCH}_2\text{CH}_2\text{CO}_2\text{H}$ Which reagents could be used in this synthesis?
- Astep 1: $\text{HCN(g)}$; step 2: $\text{HCl(aq)}$
- Bstep 1: $\text{HCO}_2\text{Na(aq)}$; step 2: $\text{HCl(aq)}$
- Cstep 1: $\text{KCN(alcoholic)}$; step 2: $\text{H}_2\text{SO}_4\text{(aq)}$
- Dstep 1: $\text{NaOH(aq)}$; step 2: $\text{K}_2\text{Cr}_2\text{O}_7/\text{H}_2\text{SO}_4\text{(aq)}$