The Serpent Mound in Southern Ohio Suggests What About Hopewell

The Serpent Mound in southern Ohio suggests what about Hopewell society?

A) The Hopewell worshiped some type of serpent deity.
B) The Hopewell likely made great use of slave labor.
C) The Hopewell had contact with the Maya, who passed on their knowledge of math and astronomy.
D) The Hopewell possessed a level of social complexity well-developed enough to organize the construction of a complicated structure with cultural significance.