Answer:
Huge tunnels were built for sewer lines.
New aqueducts brought fresh water from hundreds of miles away.
Broad boulevards were constructed.
Explanation: I just took the test and I had two questions that were similar to that and those were the answers that were correct.
The answer to your question is number 4
The Kansas-Nebraska Act<span> was passed by the U.S. Congress on May 30, 1854. It allowed people in the territories of </span>Kansas<span> and</span>Nebraska<span> to decide for themselves whether or not to allow slavery within their borders. The </span>Act<span> served to repeal the Missouri Compromise of 1820 which prohibited slavery north of latitude 36°30´.</span>
I believe the correct answer is B.
It would be the development in agricultural knowledge/technology
Development in agriculture enable hunter/gatherer society to shift their behavior. Before this, they had to keep moving from one place to another in order to seek food to live.
After the development in agricultural knowledge/technology, the society now can stay in one exact place for a long period of time and relied on agricultural product as their main source food.
After living in one same place for a long time, the needs to build things to accommodate their living start to arise. They start to built several things and repeat the process every year. In the end, large cities were developed from the initially small hunter/gatherer society.
