The Enlightenment was a European age of reason, where politics, philosophy, and science radically changed. During this period, Europe questioned authority and embraced individual thought and humanity. This period produced a plethora of books, essays, inventions, laws, scientific findings, and revolutions, such as the American and French Revolutions, which were influenced heavily by the Enlightenment period.
This is a bit subjective, but one could argue that the Fourteenth Amendment, which was one of the Reconstruction amendments, had the biggest impact on American history since it declared that all American citizens must have equal rights and protections under the law.
False, the corpus callosum is used to communicate between both hemispheres of the brain, the tissue on the outermost layer of the cerebrum is called the cerebral cortex.