Based on Piaget's theory, which of the following indicates that a child has shifted from the concrete operational stage to the formal operational stage?

This understanding reflects conservation, a key concept in the concrete operational stage. Children in this stage can grasp that physical properties remain constant despite changes in form or appearance, but it does not demonstrate the advanced reasoning characteristic of the formal operational stage.

This ability also pertains to conservation and is a hallmark of the concrete operational stage. It shows that the child can think logically about the physical characteristics of objects, but it does not encompass the abstract reasoning required in the formal operational stage.

While this skill demonstrates classification and categorization, which are common in concrete operational thinking, it does not reflect the ability to engage in abstract, systematic problem-solving that defines the formal operational stage.