The best method for the separation of naphthalene and benzoic acid from their mixture is :

To separate naphthalene and benzoic acid, we need to consider the properties of both substances. Naphthalene is a non-polar compound that sublimes easily, whereas benzoic acid is a polar compound that does not sublime. Sublimation is the transition of a substance from the solid to the gas phase without going through the liquid phase. Given that naphthalene sublimes and benzoic acid does not, sublimation can be used to separate these two compounds. Therefore, the correct answer is option (D) sublimation. Think of it this way: the difference in sublimation properties between naphthalene and benzoic acid provides a straightforward method for their separation.