I think the correct answer would be the last option. In this case, spanking was an unconditioned stimulus for Colin's fear. These are stimuli that are natural, automatic and are unconditional that would trigger responses. An example would be when you smell your favorite food, you suddenly feel hunger.
To establish a settlement, means to bring in a relatively group of large people who build houses, have jobs, form a society, and inhabit this area for a long period of time.
Sumerians were known for two inventions:
irrigation, that is bringing water to crops that would otherwise not have access to it
and writing: cuneiform, one of two first writing systems on earth (the other being hieroglyphs).
The author means by the phrase that People were able to choose who would lead their governments.
Explanation:
In the 20th century there were a lot of new nations that were formed out of old imperialistic colonies and most of them adopted, or ended up adopting a democratic system of governance where the people have the right to choose who would govern over them and the positions are rotating.
This is something that could be called to have given greater ability for the people to govern their own lives and the author has teemed the century thus as the century where the [power went to the people.
