Sam is at home with his two children, 3-year-old Daria and 6-week-old Keith. Sam is reading a story to Daria when baby Keith wakes up and screams for his bottle. Daria gets very upset when Sam leaves her to tend to the baby. Sam tries to explain to his daughter that her baby brother can’t wait, but Daria continues to insist. Sam is concerned that Daria is not accepting her new baby brother. Based on your understanding of preschoolers cognitive development, what would you tell Sam?