Which of the following is prohibited for licensees to use in performing cosmetology services?

The correct choice is the use of MMA, which refers to methyl methacrylate. This substance is prohibited for use by licensees in performing cosmetology services due to its potential health risks. MMA can cause severe allergic reactions and is associated with detrimental effects on both nails and the surrounding skin. Additionally, its use can lead to legal repercussions for cosmetology professionals, as many states regulate the substances that can be safely used in salons to protect both clients and practitioners.

Understanding the context of why MMA is prohibited highlights the importance of safety and public health in the cosmetology field. Proper knowledge of materials and substances that are safe versus those that pose risks is essential for compliance with regulations. This helps ensure a safe environment for both professionals and clients.