According to Piaget, during the formal operational stage people begin to understand mathematical operations involving sets. adhere to social norms. distinguish between good and bad behaviors. reason abstractly. become aware of the positive and negative consequences of their own behaviors.

reason abstractly.

Explanation:

Formal operational stage: In psychology, the term "formal operational stage" is one of the distinct stages in the cognitive development theory that includes a total of four stages and was proposed by a famous psychologist named Jean Piaget.

According to Piaget, the formal operational stage begins at the age of twelve years and lasts through adulthood. At this stage, an thinks in a more advanced or sophisticated manner. Adolescents at this stage gains capability to think abstractly by manipulating ideas and in the absence of any concrete manipulation.

In the question above, the given statement signifies "reason abstractly".