Final answer:
The nurse should instruct the parent to immediately call the Poison Control Center after a 2-year-old child has ingested several multivitamins with iron, which could potentially exceed the child's daily iron requirement and cause poisoning.
Step-by-step explanation:
When a 2-year-old child has ingested several multivitamins with iron, the most appropriate response for a nurse to give to the parent is to Call the Poison Control Center. Iron poisoning can be potentially serious, especially in young children, and the amount of iron that could be ingested in several multivitamins may exceed the daily requirement for a child of that age. It's also important for the parent to avoid giving any therapies such as emetics or orange juice without instruction from a healthcare professional or poison center. Immediate contact with professionals who can provide specific instructions and who may need to monitor the child's iron levels or other vitals is crucial.