What common contagious disease can prevent a professional from servicing a client?

The correct choice is ringworm because it is a highly contagious fungal infection that affects the skin, hair, or nails. In a professional setting, especially in beauty and wellness services, if someone has ringworm, it poses a significant risk of transmission to both clients and other professionals. This is particularly important in environments where skin-to-skin contact or shared tools and surfaces occur, as ringworm can easily spread through these means.

While chickenpox can also prevent a professional from servicing clients, it primarily poses a risk when the infected individual is symptomatic and is generally more concerning during the initial stages. The flu can certainly make a person too ill to work, but it is not as directly transmitted through physical contact as ringworm. Candidiasis, although an infection that affects many people, is not as contagious or easily transmitted in a professional setting. For the safety and health of clients, infected professionals must refrain from providing services to prevent the spread of infectious diseases, and ringworm is a prime example of a condition that mandates such a precaution.