Steam distillation process cannot be used for purifying which of the following?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$:
Assertion $(A):$ $A$ simple distillation can be used to separate a mixture of propanol and propanone.
Reason $(R):$ Two liquids with a difference of more than $20^{\circ}C$ in their boiling points can be separated by simple distillation.
In the light of the above statements,choose the most appropriate answer from the options given below:

Explain the process of fractional distillation.

Describe the crystallisation technique used for the purification of organic compounds.

Which technique among the following is most appropriate for the separation of a mixture of $100 \ mg$ of $p-$nitrophenol and picric acid?

Which of the following can be purified by sublimation?