The reagent (s) used for the conversion of benzene diazonium hydrogensulfate to benzene is $/$ are -

• A

  $\mathrm{H}_{2} \mathrm{O}$
• Correct answer
  B

  $\mathrm{H}_{3} \mathrm{PO}_{2}+\mathrm{H}_{2} \mathrm{O}$
• C

  $\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}$
• D

  $\mathrm{CuCl} / \mathrm{HCl}$

Hence, the correct answer is option: 'B'.