Which of the following will give propyne on hydrolysis? 

• A

  ${\text{Be}}_{\text{2}}\text{C}$

• B

  ${\text{CaC}}_{\text{2}}$

• C

  ${\text{Al}}_{\text{4}}{\text{C}}_{\text{3}}$

• D

  ${\text{Mg}}_{\text{2}}{\text{C}}_{\text{3}}$