Which of the following products cannot be reused for application?

The correct answer identifies cuticle remover as a product that cannot be reused for application. This is primarily due to sanitation and hygiene concerns. Cuticle remover typically contains active chemicals that are designed to break down the bonds in the cuticle—an area around the nail that can harbor bacteria and fungus. Once used on a client's nails, any residue left in the applicator, container, or brush can become contaminated, posing a risk of infection or irritation if applied to another client.

While products like hair color, shampoo, and conditioner might be mixed or applied in ways that can allow for reuse, cuticle remover is usually applied directly to skin or nails. Safeguarding against the transfer of bacteria between clients is critical in cosmetology practices, which is why cuticle remover should be dispensed in single-use applications or cleaned thoroughly between uses to ensure safety and health standards are maintained.