What ingredient in nail polish remover is noted to work quickly and effectively?

Acetone is the primary ingredient in many nail polish removers that is known for its ability to work quickly and effectively in dissolving nail polish. This solvent is highly efficient at breaking down the compounds found in nail polish, allowing it to remove even the most stubborn formulas with minimal effort. The fast-acting nature of acetone makes it a popular choice among both professionals and consumers in the beauty industry.

Other ingredients listed do not serve the same function. For example, antiseptics are used to prevent infection and are not designed for removing nail polish. A styptic pencil helps to stop bleeding from small cuts and is not relevant in the context of nail polish removal. Onyx, on the other hand, is a type of gemstone and does not have any properties that relate to nail polish or its removal. Therefore, acetone stands out as the best answer for its specific effectiveness in this application.