What core idea does Thoreau present in Walden about simplicity and nature?

What core idea does Thoreau present in Walden about simplicity and nature?

• A. That wealth and social status are the keys to happiness in nature.
• B. That nature should be controlled by mankind to maximize comfort.
• C. That modern conveniences are essential for moral growth.
• D. That simple living in harmony with nature fosters independence and clarity.

Answer: (D)