A previously healthy 6-year-old boy had nasal obstruction, rhinorrhea and sore throat for 3 days. There is no fever, no rash and no abdominal pain. No abnormalities on auscultation of lung and heart. The most likely diagnosis is
选项：

A: Acute URTI;
B: Allergic rhinitis;
C:Measles;
D: Acute appendicitis;
E: Acute bronchitis