At $27^{\circ} \mathrm{C}$, two liquids A and B form an ideal solution with mole fractions 0.67 and 0.33 respectively. If the vapour pressure of pure $A$ and $B$ at $27^{\circ} \mathrm{C}$ are $300 \mathrm{~mm}$ and $450 \mathrm{~mm}$ respectively, the total vapour pressure of the solution in $\mathrm{mm}$ is:

• Correct answer
  A

  $349.5$
• B

  $700$
• C

  $249.5$
• D

  $148.5$

Hence, the correct answer is option: 'A'.