What is the common name for a condition caused by a fungus?

The condition caused by a fungus that is commonly known is ringworm. This name can be misleading, as it does not refer to a worm at all but rather to a fungal infection that affects the skin. The term "ringworm" derives from the circular, ring-like appearance of the rash that often occurs on the skin when this infection is present. Ringworm can affect various parts of the body, including the scalp, feet (commonly known as athlete’s foot), and the body in general. Symptoms may include red, itchy, and scaly patches that resemble rings.

The other choices represent different conditions not caused by fungi. A skin rash can be a result of numerous factors, including allergies or irritants, but it is not specific to fungal infections. Warts are caused by a viral infection, specifically the human papillomavirus (HPV). Psoriasis is an autoimmune condition characterized by rapid skin cell turnover that leads to thick, red patches covered with white scales, and it is not caused by a fungus. Thus, ringworm is correctly identified as the fungal condition being referenced in the question.