Answer:
The answer is the preoperational stage.
Explanation:
Object permanence is a concept that explains all objects conserve their original properties, even if the parts are separated or distributed in a different way. For example, a child that understands that a chocolate bar sliced in four pieces is still the same amount of chocolate, has likely understood the concept of object permanence.
According to Piaget, the understanding of object permanence should appear during the the sensorimotor stage. In the example, Antoinetta is still probably in this phase, and about to transition to the preoperational stage.
