Which of the following should be applied to the skin prior to the chemical peel?

The appropriate application prior to a chemical peel is a balancing solution. This product typically serves to prepare the skin for the treatment by ensuring that the skin's pH is at an optimal level for the chemical peel to be effective. A balancing solution can also help to remove any excess oils or residues on the skin, which allows for better penetration of the peel solution, enhancing its efficacy and reducing the potential for irritation.

Using a balancing solution helps to create a more uniform surface for the peel, thereby promoting more even exfoliation. It can also assist in minimizing the risk of adverse effects, ensuring that the skin is in a well-conditioned state to tolerate the upcoming chemical process.

While moisturizers and retinol are beneficial for skin health, their application just before a chemical peel is not standard practice, as they can interfere with the peel's action. Sunscreen is important for protecting the skin from UV rays but is typically advised for post-peel care rather than pre-treatment. The focus prior to a peel is on creating the right environment for the treatment to be successful, which is why a balancing solution is the most suitable choice.