A

Herpangina classically presents in toddlers after a brief febrile URI with small, discrete vesicles that rapidly ulcerate on the soft palate, tonsillar pillars and posterior pharynx, exactly as described in this 3-year-old child; other options do not fit this posterior-oropharyngeal vesicular pattern (scarlet fever shows a scarlatiniform rash, rubella causes a mild exanthem, and herpetic gingivostomatitis involves widespread anterior oral mucosa and gingiva). [Li, 2016, 27752104] [Yu, 2020, 31347021]