Correct option is B. $$(A) \rightarrow (ii), (B) \rightarrow (iv), (C) \rightarrow (iii), (D) \rightarrow (i)$$
(A) Liquid $$\rightleftharpoons $$ Vapour
Equilibrium exists at the boiling point.
(B) Solid $$\rightleftharpoons $$ Liquid
Equilibrium exists at the melting point.
(C) Solid $$\rightleftharpoons $$ Vapour
Equilibrium exists at the sublimation point.
(D) Solute $$\rightleftharpoons $$ Solute(solution)
Equilibrium exists in a saturated solution.