Based on the second short video, what problems were ‘progress’ trying to solve after the year 1900?

Explanation:

In the early 1900s, the United States entered a period of peace, prosperity, and progress. In the nation's growing cities, factory output grew, small businesses flourished, and incomes rose. As the promise of jobs and higher wages attracted more and more people into the cities, the U.S. began to shift to a nation of city dwellers. By 1900, 30 million people, or 30 percent of the total population, lived in cities.

The mass migration of people into the cities enriched some people but caused severe problems for others. For the emerging middle class, benefiting from growing incomes and increases in leisure time, the expanding city offered many advantages. Department stores, chain stores, and shopping centers emerged to meet the growing demand for material goods. Parks, amusement parks, and baseball stadiums were built to meet aesthetic and recreational needs. Transportation systems improved, as did the general infrastructure, better meeting the increased needs of the middle and upper class city dwellers.

Thousands of poor people also lived in the cities. Lured by the promise of prosperity, many rural families and immigrants from throughout the world arrived in the cities to work in the factories. It is estimated that by 1904 one in three people living in the cities was close to starving to death. For many of the urban poor, living in the city resulted in a decreased quality of life. With few city services to rely upon, the working class lived daily with overcrowding, inadequate water facilities, unpaved streets, and disease. Lagging far behind the middle class, working class wages provided little more than subsistence living and few, if any, opportunities for movement out of the city slums.

(hope this helps can i plz have brainlist :D hehe)

where is the subject? hahahaha

1) she is extremely upset