Answer:
(E) They contained utilitarian items made of non-local materials.
Step-by-step explanation:
Based from the passage provided in the question, option A cannot be the right answer as these mounds are't sewed primarily as burial grounds. They were rather sewed as "substructures for buildings important to civic and religious affairs". Option B is also wrong as there is no mention of them being constructed in the key locations of the community. Option C and D are also wrong as we find no mention of these mounds as being storage places. Option E is the right answer as it directly mentions the presence of the items made of non- local materials.