Which of the following statements are correct?
$A$. Glycerol is purified by vacuum distillation because it decomposes at its normal boiling point.
$B$. Aniline is purified by steam distillation as it is immiscible in water.
$C$. Ethanol can be separated from an ethanol-water mixture by azeotropic distillation because it forms an azeotrope.
$D$. An organic compound is pure if the mixed $M.P.$ remains the same.
Choose the most appropriate answer from the options given below:

• A
  $A, B, C$ only
• B
  $A, C, D$ only
• C
  $B, C, D$ only
• D
  $A, B, D$ only