Acetone
Both are correct! Ethyl acetate and acetone are common solvents that may be present in nail polish as well as in nail polish remover; the choice of the solvent depends on the commercial brand. Ethyl acetate and acetone are solvents for the lacquer and pigments that make up nail polish. Nail polish hardens when the solvent evaporates and leaves behind the lacquer, which can be re-dissolved and removed by applying the solvent again. Acetone is a common solvent in chemistry laboratories and is also used in the manufacture of polymers and explosives. It is industrially produced by bacterial fermentation.