There are a few staple crops that have been especially vital to the growth of the human population - wheat, barley, rice, potatoes, maize, yams, bananas, beans. Each of these crops first originated in a particular part of the world and then, through human influence, spread around the world. Wheat and barley were first grown in the Middle East during and after the Neolithic Revolution.

Camels were first domesticated in Arabia approximately four thousand years ago. The domestication of camels has been vital to the development of the Middle East. Camels are particularly useful for carrying cargo over long distances due to their ability to survive in the desert. Camel caravans have been an important part of Middle Eastern Empires since the Persians.

Fire improved the diet of early humans. It allowed humans to cook meat as opposed to eating it raw, which killed dangerous bacteria that would have otherwise been present in the food. Fire also allowed humans to cook dry meat to preserve, creating a surplus of food that did not previously exist. Humans could also use fire to clear fields and improve fertility of land, allowing them to harvest more crops.

While all of the answer choices are significant to human history, agriculture changed the history of humankind the most dramatically because it allowed people to settle in one place, which before 8000 BCE was not something that humans were capable of doing.

Yu the Great is considered to be the (somewhat legendary) founder of the Xia Dynasty and of the Chinese state. Yu the Great might best be understood as a reforming bureaucrat. His state building efforts were primarily concentrated on combating and preventing the flooding of the Yellow River. In organizing the population to resist the advances of the seasonal floods, Yu helped found the Chinese state.

Horses were first domesticated on the great Eurasian steppes of Central Asia approximately six thousand years ago. The domestication of the horse had a profound impact on the nature of human development - particularly in terms of agriculture, transportation, and warfare.

Sheep were the first animals to be domesticated for food, approximately eight thousand years ago. The domestication of animals like sheep and pigs has been instrumental to the growth of human society.

Evidence suggests that elephants were first domesticated in India approximately three thousand years ago. The domestication of elephants led to elephants being used on the battlefield by armies in India and by the Carthaginians in North Africa.

Dogs were the earliest animal to be domesticated by human society. In the paleolithic era, before the establishment of the first cities and great civilizations, man and wolf were frequent collaborators - working together during hunting. From this partnership, and the domestication of wolves, emerged dogs.

Sheep were the first animals to be domesticated, over eight thousand years ago, at the same time as the Neolithic Revolution was taking place. They were first domesticated in modern-day Iraq - so the correct answer is the Middle East.