A, B

B, C

C, D

A, D

(i) $\left(\mathrm{BH}_3\right)_2$ (ii) $\mathrm{H}_2 \mathrm{O}_2 / \mathrm{OH}^{-}: \mathrm{HCl}, \mathrm{ZnCl}_2$

(i) $\left(\mathrm{BH}_3\right)_2$ (ii) $\mathrm{H}_2 \mathrm{O}_2 / \mathrm{OH}^{-}: \mathrm{NaCl}$

(i) dil. $\mathrm{H}_2 \mathrm{SO}_4: \mathrm{HCl}, \mathrm{ZnCl}_2$

(i) dil. $\mathrm{H}_2 \mathrm{SO}_4$ : Conc. HCl

secondary alkyl halide

primary alkyl halide

tertiary alkyl halide

benzylic halide