At a college graduation ceremony, each graduate is handed a diploma and sunflower. Aaron, Fiona, and Noor are three graduates. Only Fiona is allergic to sunflowers. As she exits the stage, Fiona sneezes but Aaron and Noor do not. Why does Fiona sneeze but not the other two?

Fiona is allergic to sunflowers while the other two are not. After she received a sunflower on the stage, it caused her to sneeze.