What can occur if a practitioner uses a back-and-forth motion while filing the natural nail?

Using a back-and-forth motion while filing the natural nail can lead to disrupted plate layers, which is why the correct answer is this option. The natural nail is made up of layers of keratin, and filing against the natural grain can cause those layers to separate and fray. This not only weakens the nail but can also lead to splitting and peeling, compromising the overall health of the nail.

Practitioners are usually trained to file in one direction to maintain the integrity of the nail structure. This method helps ensure smoother edges and prevents damage to the delicate layers of the nail plate.

While some might think that a back-and-forth motion might improve shine or nail strength, the damage it causes to the plate layers contradicts those benefits. The same logic applies to longer nail growth; using an improper filing technique can actually hinder the growth and health of the nails.