${\mathrm{CaC}}_2\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{A}\underset{{\mathrm{HgSO}}_4, {60}^{\mathrm{o}}\mathrm{C}}{\overset{\mathrm{dil}. {\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\mathrm{B}\left(\mathrm{final}\right).$ The compound ‘B’ is the reductive ozonolysis product of

• A

  Ethene

• B

  Isobutene

• C

  2-butene

• D

  1-butene