Consider two containers $A$ and $B$ containing identical gases at the same pressure,volume and temperature. The gas in container $A$ is compressed to half of its original volume isothermally while the gas in container $B$ is compressed to half of its original volume adiabatically. The ratio of final pressure of gas in $B$ to that of gas in $A$ is

• A
  $2^{\gamma-1}$
• B
  ${\left( {\frac{1}{2}} \right)^{\gamma - 1}}$
• C
  ${\left( {\frac{1}{{1 - \gamma }}} \right)^2}$
• D
  ${\left( {\frac{1}{{\gamma - 1 }}} \right)^2}$