Missouri Board of Cosmetology Practice Exam

Onychomycosis, also known as toenail fungus, is a common infection caused by a type of fungus called dermatophytes. These fungi thrive in warm and moist environments, making your toenails the perfect place for them to grow. While options A, C, and D may seem plausible, a virus, nutrition deficiency, or careless filing are not known to cause onychomycosis. It is important to note that certain health conditions, medications, and lifestyle factors can increase the risk of developing this infection, but the direct cause is typically a type of fungus. Therefore, option B, a parasite, is the most accurate answer.