Final answer:
In Piaget's theory of cognitive development, the stage in which children understand rules and realize they must adhere to them is the concrete operational stage. The correct option is b) Concrete operational stage
Step-by-step explanation:
According to Piaget's theory of cognitive development, the stage at which children understand rules and realize they must adhere to them in order to maintain their interactions with others is the concrete operational stage.
This stage occurs from about 7 to 11 years old. Children in this stage can think logically about real events, perform mathematical operations, and understand concepts like conservation.
They are also able to understand the principle of reversibility, which means that objects can be changed and then returned back to their original form or condition.
For example, children in this stage would understand that pouring water back into the original glass does not change the amount of water. The correct option is b) Concrete operational stage