Which of the following refers to a common acute viral infection in children?

Fifth Disease, also known as erythema infectiosum, is indeed a common acute viral infection that primarily affects children, particularly those aged 5 to 15 years. It is caused by parvovirus B19, and one of its hallmark features is a "slapped cheek" rash that appears in children after a mild febrile illness. The infection is typically mild and self-limiting, but it can have more serious consequences in certain populations, such as pregnant women or individuals with immunocompromised systems.

In contrast, while Measles, Scarlet Fever, and Rubella can all affect children, they either have different transmission modes or are less common as acute viral infections. Measles is a highly contagious viral illness but is accompanied by more severe symptoms and complications. Scarlet Fever is bacterial, caused by Streptococcus pyogenes, and Rubella, while also a viral infection, is less frequently seen because of widespread vaccination efforts. Thus, Fifth Disease stands out as a well-recognized viral illness that fits the criteria outlined in the question.