The mound builders were american indian groups who a. built irrigation systems for farming. b. developed sophisticated art. c. stayed in their own communities. d. flourished in the eastern river valleys.

The correct answer is D. The Mound Builders were American Indian groups who flourished in the eastern river valleys.

Explanation:

The culture of the mounds is a pre-Columbian archaeological culture that developed in the south and southeast of the current United States. Mound Builders were the carriers of this culture, which probably belonged to different ethnic and linguistic groups. The highest concentrations of burial mounds occur in the state of Ohio, where more than 10,000 have been located. One of the most representative sites of mound cultures is Cahokia, in the Mississippi Valley.

answer; i believe the answer is (mesopotamia); modern day

the ss was the main organization responsible for the genocidal murder of around six million people of european ethnic minorities, essentially jews, in the holocaust. the members of all its branches committed war crimes and crimes against humanity during the second world war (1939-1945). likewise, the ss were involved in commercial enterprises and exploited the inmates of the concentration camps as slave laborers.

the tortures and assassinations committed by the ss were the result of an ideology developed long before the armed conflict, this ideology was based on the racial supremacy of the germans over the rest.