The correct answer is A. Sublimation.
Sublimation is the process of a solid turning directly into a gas without passing through the liquid state. It is a physical change that occurs when a substance has a high vapor pressure at a relatively low temperature. Camphor is a solid that sublimes at room temperature, so it can be purified by sublimation.
Fractional crystallisation is a
process used to separate mixtures of two or more substances that have different solubilities in a solvent. The mixture is dissolved in a solvent and then cooled slowly. The substance with the lower solubility will crystallize out first, followed by the substance with the higher solubility.Fractional distillation is a process used to separate mixtures of two or more liquids that have different boiling points. The mixture is heated and the vapor is condensed into a liquid. The liquid with the lower boiling point will vaporize first, followed by the liquid with the higher boiling point.
Steam distillation is a process used to separate mixtures of a solid and a liquid that are immiscible in water. The mixture is heated with steam and the vapor is condensed into a liquid. The solid will remain in the solid state.
In conclusion, impure camphor is purified by sublimation.