Answer: The preoperational stage .
Step-by-step explanation:
This stage occurs when the child is around two to seven. The child learn to understand symbolic infromation but not concrete logic
Understanding Conservation
At this stage they don't understand the law of conservation in such that the weight of a substance doesn't change because the shape is changed or altered. For example if an equal amount of liquid is poured in glasses of different shapes such as one glass being tall and thin whilst the other is short and wide the child at this stage doesn't understand that the amount of liquid is conserved in either glass.
At this stage Adam doesn't understand that it doesn't matter that the shape of the pie is altered but the amount one gets will still be the same , just because it is split into two that doesn't change its mass or quantity , the mass of the pie is conserved irrespective of the shape.