Which of the following best describes a true cultural hearth?
a. An urban area with complex religious and social systems and a well-established civilization that formed independent of any other existing civilization.
b. An area that conquistadors overthrew and established as their own land.
c. A region that is considered underdeveloped and provides agricultural goods to other parts of the country.
d. A group of people who travel seeking the Imperial "G" Trifecta: Gold, God, and Glory.