The answer is A. It showed that racial segregation was constitutional. Plessey was 1/8 Afro-American and 7/8 White. Lousiana law in 1890 clasified him as Afro-American. He was arrested because he didn't want to sit in the seats of Afro.American citizens's wagons.
Earthen mounds
The city of Cahokia was founded by Mississippian culture near the current day city of St. Louis, MO.
Cahokia is known for the large earthen mounds created by tribes of the Mississippian flood plains. The large mounds were used as burial sites as well as tributes to the gods of the Cahokian people. This large site is believed to be the center of Mississippian tribes living up and down the river and connected by their mound building culture.