Tara's friend, Sally, came to school with a cold and sat in the desk next to Tara's all morning blowing her nose. At lunch, they went outside to sit in the sun and eat. Sally blew her nose again and then gave Tara her cookie since she didn't feel like eating it. Tara ate it and then carried Sally's things back inside for her. Several days later Tara came down with the cold. At what point was it most likely that the virus infected Tara?