The answer for this question is: <span>the election of Abraham Lincoln as President
Abaraham Lincoln was always known as someone that really see slavery as something that undermines human's value.
Not long after elected as president, Abraham Lincoln made several policies that make it harder for the southern states to keep their slaves, which led to the first secession.</span>
The creation of distinctive classes in the North drove striking new cultural developments. Even among the wealthy elites, northern business families, who had mainly inherited their money, distanced themselves from the newly wealthy manufacturing leaders. Regardless of how they had earned their money, however, the elite lived and socialized apart from members of the growing middle class. The middle class valued work, consumption, and education and dedicated their energies to maintaining or advancing their social status. Wage workers formed their own society in industrial cities and mill villages, though lack of money and long working hours effectively prevented the working class from consuming the fruits of their labor, educating their children, or advancing up the economic ladder.
The best and most correct answer among the choices provided by the question is the first choice. <span>Urban planning helped many of the larger cities control the problems brought by rapid population growth. </span><span>I hope my answer has come to your help. God bless and have a nice day ahead!</span>
