What condition prevents work from being performed on a patron?

The correct answer is visible disease because it directly represents a potential health risk to both the patron and the service provider. In many professional settings, particularly in those involving direct physical contact, visible signs of illness can indicate contagious conditions that may pose a risk to others. For instance, if a patron has an observable rash or signs of an infectious disease, performing work on them could result in the transmission of that illness, thus justifying a refusal of service until the condition is no longer present.

Emotional distress, although it may affect a patron's well-being, does not pose a physical risk that warrants preventing work from being conducted. Similarly, while allergies are important to consider—for instance, if a patron has allergies to certain products or ingredients—they do not universally prevent work from being performed unless they are severe and visibly evident. Recent injuries could require special accommodations or care in providing services, but they do not automatically prevent service unless they pose a direct health risk, which is not always the case. Therefore, visible disease is the condition that most clearly necessitates the refusal of service to ensure safety and health for all parties involved.