Which of the following must be diluted to avoid irritation?

Essential oils are concentrated plant extracts that contain potent compounds. When used directly on the skin, they can cause irritation, allergic reactions, or sensitization due to their high concentration. Therefore, it is essential to dilute essential oils with a carrier oil or another medium before application to ensure safety and reduce the risk of adverse reactions. Dilution helps to balance their therapeutic properties while minimizing potential side effects.

In contrast, acetone and alcohol, while they may cause some drying or irritation on their own, do not typically require dilution for use in nail services or sanitation. Gel polish is designed to be used as is, directly applied to the nail without dilution to maintain its chemical formula and performance.