An 11-year-old girl is brought to the clinic by her mother with a 3-day history of an erythematous rash on her trunk and extremities. The mother reports that 1 week ago, the patient developed low-grade fever (38.1°C), rhinorrhea, and mild headache that resolved over 2 days. Two days ago, a bright red facial rash appeared that spared the perioral region. On examination, vital signs are normal except for a temperature of 37.8°C (100°F). The facial rash is well-demarcated and blanching. On her forearms and thighs, the examiner notes a lace-like reticular pattern of erythema with central clearing. She reports mild pruritus but denies oral lesions, arthralgia, or conjunctivitis. Which of the following is the most likely diagnosis?

1. A)Rubella
2. B)Measles
3. C)Erythema infectiosumGABARITO
4. D)Scarlet fever
5. E)Drug reaction (ampicillin)