In Piaget's theory, which stage includes conservation and reversibility?

• A. Sensorimotor
• B. Preoperational
• C. Concrete Operational
• D. Formal Operational

Answer: (C)

Conservation and reversibility signal the emergence of logical thinking about concrete objects and events. In this stage, children understand that quantity stays the same even when the appearance changes (for example, when liquid is poured into a different-shaped container, the amount remains the same) and that operations can be reversed to return to the starting state (you can pour water back or reform flattened clay to its original shape). This allows them to reason about real-world situations with consistency, rather than just what they see at the moment. Earlier stages show limited conservation because of centration and irreversibility, and later stages move into abstract thinking, but conservation and reversibility specifically characterize the concrete operational level.