At the beginning of the twentieth century (1901–2000), the US was reaching adulthood. Unequal distribution of wealth and income persisted. One percent of American families possessed nearly seven-eighths of its wealth. Four-fifths of Americans lived on a survival level while a handful lived in incredible luxury. In 1900, Andrew Carnegie earned about $23 million; the average working man earned $500. The wealth of a few was increased by the exploitation of women and children. One out of five women worked for food rather than fulfillment, earning wages as low as $6 a week. The sacrifice of the country’s young to the god of economic growth was alarming. One reporter undertook to do a child’s job in the mines for one day and wrote, “I tried to pick out the pieces of slate from the hurrying stream of coal, often missing them; my hands were bruised and cut within a few minutes; I was covered from head to foot with coal dust, and for many hours afterwards I was expectorating some of the small particles of anthracite I had swallowed.” Working conditions were equally horrifying in other industries, and for many Americans, housing conditions were as bad or worse. One investigator described a Chicago neighborhood, remarking on the “filthy and rotten tenements, the dingy courts and tumbledown sheds, the foul stables and dilapidated outhouses, the broken sewer pipes, and piles of garbage fairly alive with diseased odors.” At the same time, the Vanderbilts summered in a “cottage” of seventy rooms, and wealthy men partied in shirts with diamond buttons worth thousands of dollars. The middle class experienced neither extreme. Its members did have their economic grievances, however. Prosperity increased the cost of living by 35 percent in less than a decade, while many middle-class incomes remained fairly stable. Such people were not poor, but they believed they were not getting a fair share of the prosperity.

Which sentence best expresses the implied main idea of this passage?

A) In 1901, the United States was finally becoming a strong country.

B) At the beginning of the twentieth century, there were wide gaps between the income levels of America’s rich and poor.

C) In 1901, the United States had three distinct classes of citizens: the rich, the middle class, and the poor.

D) At the beginning of the twentieth century, a number of significant problems existed in the United States.