A nurse is assessing a child and notes Koplik spots. In which of these communicable diseases are Koplik spots present?

Rationale: A: Measles (rubeola): Koplik spots are small, bluish-white lesions with a red base that appear on the buccal mucosa, typically near the molars. They are a hallmark sign of measles and usually appear 1–2 days before the characteristic maculopapular rash develops. Their presence strongly supports a measles diagnosis in a symptomatic child. B: Chicken pox: This viral illness caused by varicella-zoster virus is characterized by a vesicular rash in various stages of healing, beginning on the trunk and spreading outward. Oral lesions may occur but they are vesicular, not the pinpoint bluish-white lesions. C: Exanthema subitum (roseola): Caused most often by human herpesvirus 6, roseola presents with high fever followed by a sudden pink maculopapular rash after the fever subsides. Koplik spots are not associated with this illness. D: Rubella: Also known as German measles, rubella presents with a fine pink rash, lymphadenopathy, and mild symptoms. There are no Koplik spots; instead, enanthem is rare and nonspecific if present