One of the two vessels of same capacity is filled with oxygen and other is with helium of same mass. Both gases are at same temperature. The ration of pressure of these gases is 

• A

  $\frac{{\mathrm{P}}_{{\mathrm{o}}_2}}{{\mathrm{P}}_{\mathrm{He}}}=\frac{1}{8}$

• B

  $\frac{{\mathrm{P}}_{{\mathrm{o}}_2}}{{\mathrm{P}}_{\mathrm{He}}}=\frac{1}{4}$

• C

  $\frac{{\mathrm{P}}_{{\mathrm{o}}_2}}{{\mathrm{P}}_{\mathrm{He}}}=\frac{4}{1}$

• D

  $\frac{{\mathrm{P}}_{{\mathrm{o}}_2}}{{\mathrm{P}}_{\mathrm{He}}}=\frac{8}{1}$