Which nail tool is primarily used for shaping the nails?

The nail file is primarily used for shaping the nails because it is specifically designed to smooth and refine the edges of the nails. When a nail file is moved across the edge of the nail, it removes small amounts of the nail's surface to create the desired shape, whether that is square, round, or oval.

This tool is essential in nail care as it allows for precision and control in shaping, which is important for achieving a polished and well-groomed appearance. Nail files come in various grits and materials, which can cater to different nail types and preferences, enhancing their versatility in shaping.

The other tools mentioned serve different purposes; for instance, a nail clipper is primarily for cutting the nails rather than shaping them, a cuticle pusher is used to push back and manage cuticles, and a nail brush is meant for cleaning the nails and nails beds rather than shaping. Therefore, the nail file stands out as the correct answer for its specific purpose in shaping nails.