The coefficient of apparent expansion of a liquid when determined using two different vessels $A$ and $B$ are ${\gamma _1}$ and ${\gamma _2}$ respectively. If the coefficient of linear expansion of vessel $A$ is $\alpha $,the coefficient of linear expansion of vessel $B$ is

• A
  $\frac{{\alpha {\gamma _1}{\gamma _2}}}{{{\gamma _1} + {\gamma _2}}}$
• B
  $\frac{{{\gamma _1} - {\gamma _2}}}{{2\alpha }}$
• C
  $\frac{{{\gamma _1} - {\gamma _2} + \alpha }}{3}$
• D
  $\frac{{{\gamma _1} - {\gamma _2}}}{3} + \alpha $