Because it was near rivers and other geographical advantages.
The correct answer is - trade.
The Sumerians engaged in trade with their move of exchanging their surplus food for materials like the copper that they needed to develop their weapons and thus their army forces. This was a very smart move from their side because they managed to use the resource they had in abundance but was scarce in the other surrounding areas so that they take what they need to become stronger and pretty much defend more efficiently from the same people they were engaging in trade with.
Biological determinism is a canard that has repeatedly been explained away by evolutionary informed scientists since time immemorial. Humans are an inextricable mix of their genes and their environments. As a matter of fact, genes get turned on or off as a function of environmental inputs. Evolutionary-based cognitive computational systems take information from the environment to get activated. Natural selection itself, the foundational mechanism of evolution, is shaped by the selective forces within a specific environment. Hence, there is no such thing as biological determinism.
The answer is B), detente, which was established when Reagan became President.
