What does mean of this quote knowledge is power," and an educated and intelligent people can neither be held in, or reduced to slavery;

well knowledge IS power

the correct answer is individualism and exchange. at this stage, children begin to question the rules, because they can see that there is more than one side to them. different individuals have different viewpoints. they won't be able to reach this stage because of ignorance, a lack of ethics or personal biases. that is because people with that characteristiscs are not able to distinguish what is good or what is bad and they can't pursue their individual interests.