Which detail helps support the central idea of
both Section 2 and Section 3?

Answer:
D) Brain waves are very active while people are dreaming.
Explanation:
Section 2 says that the brain is changing stuff in your body while you are sleeping.
Section 3 says that your brain processes information while you are sleeping.
These two sections are saying that the brain is active whil you are dreaming.
Hope this helps!!