A nurse is caring for a child who is having a tonic-clonic seizure and vomiting. Which of the following actions is the nurse's priority?

A. Move the child into a side-lying position: This is the priority action to maintain an open airway, promote drainage of vomit, and reduce the risk of aspiration. B. Remove the child's eyeglasses: While helpful to prevent injury, it is not the priority action during an active seizure. C. Time the seizure: Timing is important to assess the duration and severity of the seizure, but it does not address immediate safety concerns like aspiration. D. Place a pillow under the child's head: While this may prevent head injury, repositioning to a side-lying position to prevent aspiration is more critical.