Pressure of $1 \ g$ ideal gas $X$ at $300 \ K$ is $2 \ atm$. When $2 \ g$ of another gas $Y$ is introduced in the same vessel at the same temperature,the total pressure becomes $3 \ atm$. The correct relationship between molar masses of $X$ and $Y$ is:

• A
  $M_Y = 2M_X$
• B
  $M_Y = 4M_X$
• C
  $M_X = 4M_Y$
• D
  $M_X = 5M_Y$