A nurse is caring for an 18-month-old toddler who has been hospitalized for 10 days. After the toddler's mother leaves the room, the nurse observes the toddler sitting quietly in the corner of the crib, sucking her thumb. When the nurse approaches the crib, the toddler turns away from the nurse. The nurse should understand that these behaviors indicate which of the following developmental reactions?

Rationale: A. Developing autonomy is shown by behaviors like wanting to do tasks independently, not by thumb-sucking or withdrawal. B. An anxiety reaction can be present, but the described behaviors (thumb-sucking, withdrawal) more specifically reflect regression. C. Regression is common in hospitalized toddlers who feel stressed or insecure. Behaviors such as thumb-sucking and withdrawal are coping mechanisms that represent reverting to earlier developmental stages. D. Resentment toward the mother is not reflected in the child’s behavior; instead, the child is using self-soothing behaviors.