How did mesopotamia change the nomadic way of life?

I believe the answer is:
agriculture and animal husbandry.

Prior to this, the main way of survival among Mesopotamian is through hunting/gathering method, but this method require members of the group to move from one place to another in pursuit of resource availability. With agriculture, they could produce their own resource, so they can afford to stay in one place for a long period of time.

Ithink the answer you are looking for is (b).