Which of the following can lead to fungal infections if not handled properly?

Nail enhancements can lead to fungal infections if they are not managed correctly. This is primarily due to the fact that nail enhancements, such as acrylic or gel applications, create an environment that can trap moisture between the enhancement and the natural nail. If moisture becomes trapped, it can lead to a breeding ground for fungi, especially if the application is not performed correctly, allowing for gaps or lifting at the edges.

It's also important to maintain proper hygiene and sanitation practices when applying and maintaining nail enhancements to minimize the risk of infection. Regular checks for any signs of lifting or damage, along with proper filing and shaping techniques, can also help prevent any conditions that may encourage fungal growth.

In contrast, while the other options can affect nail health, they typically do not carry the same risk of directly leading to fungal infections as improperly managed nail enhancements do. For instance, eponychium, dry cuticles, and brittle nails are more about structural and aesthetic concerns rather than creating an environment that promotes fungal growth.