Although this depends slightly on what period you're referring to during this time, the best answer would be that "Immigrants" made up the largest percentage of workers in American industry during the late nineteenth century, since the economy had shifted towards industrial output as opposed to agrarian output.
It would be the "a. Social Security Administration" that was begun during the New Deal and still exists today, since many people rely on this in order to retire later in life.
How did economic changes affect everyday life in the 1930's?
banks closed, people lost their saving and jobs, bread and soup lines were set up to feed the hungry, people lost their homes and farms
