Which of the following would most benefit a client with brittle nails?

A hot oil treatment would most benefit a client with brittle nails because it provides essential moisture and nourishment to the nail and surrounding cuticles. Brittle nails often result from a lack of hydration, which can make them weak and prone to breakage. The heat from the oil helps to open up the pores of the skin and nails, allowing the oil to penetrate deeply and effectively hydrate the nails. This treatment can improve flexibility and reduce brittleness, leading to healthier-looking nails.

In contrast, gel polish application and acrylic nail enhancement may serve as temporary cosmetic solutions rather than addressing the underlying issue of nail health. While they can enhance appearance, they don't provide the necessary moisture and nutrients that brittle nails require. Additionally, regular filing and buffing can help maintain nail appearance, but without sufficient hydration, these methods alone won't effectively strengthen brittle nails.