Which of the following treatments is appropriate for a fungal rash?

For a fungal rash, the most appropriate treatment is the application of Nystatin. Nystatin is an antifungal medication that specifically targets fungal infections, making it effective in treating conditions caused by yeast and other fungi. It works by binding to the fungal cell membrane, causing permeability changes and ultimately leading to the death of the fungal cells.

In contrast, hydrocortisone cream is a topical steroid that helps reduce inflammation and itching but does not directly address the underlying fungal infection. Antihistamines are primarily used to relieve allergic reactions and itching associated with conditions like hives or insect bites, not for fungal infections. Saline washing can help cleanse the skin but does not provide antifungal properties, which are necessary for effectively treating a fungal rash.

Therefore, Nystatin is the treatment specifically designed to combat fungal infections, making it the correct answer for managing a fungal rash.