A liquid occupies 1/3 rd of a vessel at a particular temperature. The volume of unoccupied part remains constant at all temperatures. If α is coefficient of linear expansion of vessel and ‘$\gamma$’ is coefficient of real expansion of liquid, then
 

• A

  $\gamma =3\alpha$

• B

  $\gamma =6\alpha$

• C

  $\gamma =9\alpha$

• D

  $\gamma =\alpha$