In the context of Jean Piaget's theory of cognitive development, which of the following is a key characteristic of the 'Formal Operational Stage' that distinguishes this stage from the preceding 'Concrete Operational Stage'?

According to Jean Piaget's theory of cognitive development, the most important characteristic of the formal operational stage (from approximately 11 years to adulthood) is the development of the capacity for abstract thinking and deductive reasoning. In this stage, children do not merely think about concrete or tangible objects, but become capable of solving problems logically and scientifically based on hypotheses. 'Conservation' is a characteristic of the concrete operational stage, 'object permanence' is a characteristic of the sensorimotor stage, and 'symbolic play' is related to the pre-operational stage.