In the reaction B $\underset{{\mathrm{H}}_2}{\overset{\mathrm{pd}-{\mathrm{BaSO}}_4}{\leftarrow }}{\mathrm{CH}}_3-\mathrm{C}\equiv \mathrm{C}-\mathrm{C}{\mathrm{H}}_3\underset{{\mathrm{H}}_2}{\overset{\mathrm{Na}-{\mathrm{NH}}_3}{\to }}\mathrm{A}$, A and B are

• A

  cis 2-butene

• B

  Trans-2-butene

• C

  A is cis-2-butene, B is trans – 2 – butene

• D

  A is trans – 2 – butene, B is cis -2- butene