Equal masses of methane and oxygen are mixed in an empty container at $25^{\circ}C$. The fraction of the total pressure exerted by oxygen is :

Question

( A ) $\frac{1}{3}$
( B ) $\frac{2}{3}$
( C ) $\frac{1}{2}$
( D ) $\frac{1}{3} \times \frac{273}{298}$