Predict A in the following reaction is?                                     

$\mathrm{HC}\equiv \mathrm{C}-{\mathrm{CH}}_3\underset{\mathrm{Me}-\mathrm{Br}}{\overset{{\mathrm{NaNH}}_2}{\to }}$

• A

  

• B

  

• C

  

• D

  Dimethyl acetylene