Which tool is commonly used for applying nail polish?

The tool that is commonly used for applying nail polish is a brush. This brush is typically included with the nail polish bottle and features soft bristles specifically designed to spread the polish evenly across the nail surface. The shape and flexibility of the brush allow for precision application, enabling the user to create smooth, even layers of color without excessive buildup or streaks.

In contrast, other tools listed, such as a paddle, comb, and scissors, are not suitable for this purpose. A paddle may be used in other cosmetic contexts, such as for applying certain substances, but it does not provide the fine control necessary for nail polish application. A comb is primarily used for hairstyling and will not effectively apply liquid products like nail polish. Scissors are meant for cutting materials and have no relevance in the application of nail polish. Thus, understanding the specific functions of these tools highlights why the brush is the appropriate choice for nail polish application.