Which describes a contribution of mesopotamian civilization the people invented the buddhist religion. the people used the practice of mummification to preserve the dead. the people invented the wheel to pull large loads more easily. the people created the idea of a self-governing city.

The last two answers are very tough to choose from. I think the idea of a self-governing city was not created in that region.

The people invented the wheel to pull large loads more easily. 

Why? The first evidence of wheeled vehicles appears in the second half of the 4th millennium BCE, near-simultaneously in Mesopotamia (Sumerian civilization). 

People know what happened in the past by looking at things from the past including sources (like books, newspapers, and letters) and artifacts (like pottery, tools, and human or animal remains.) ... People can learn about the past by talking to people who remember things that happened at some point in the past.