Answer:
D) Formal operation
Explanation:
Petra is able to imagine what would happen if parents were held legally responsible for the crimes of their children. She is capable of making an argument for or against this, regardless of her opinion. Petra is probably in the formal operation stage of cognitive development. This is the last stage of cognitive development according to Piaget. Kids reach this stage at approximately 12 years of age. In this stage they can think abstractly about concepts and use logical thoughts. If Petra can imagine what would happen ... she is in this stage.