Liquid $M$ and liquid $N$ form an ideal solution. The vapour pressures of pure liquids $M$ and $N$ are $450 \ mmHg$ and $700 \ mmHg,$ respectively at the same temperature. Then the correct statement is: ( $x_M =$ mole fraction of $M$ in solution; $x_N =$ mole fraction of $N$ in solution; $y_M =$ mole fraction of $M$ in vapour phase; $y_N =$ mole fraction of $N$ in vapour phase)

• A
  $\frac{x_M}{x_N} > \frac{y_M}{y_N}$
• B
  $\frac{x_M}{x_N} = \frac{y_M}{y_N}$
• C
  $(x_M - y_M) < (x_N - y_N)$
• D
  $\frac{x_M}{x_N} < \frac{y_M}{y_N}$