Final answer:
The statement likely refers to the Roaring Twenties, a period of economic growth with increasing GDP and decreasing unemployment before the Great Depression, where the GDP shrunk and unemployment soared.
Step-by-step explanation:
The statement 'GDP Increase and Unemployment during 1921-1929' seems to be a reference to the economic situation in the United States during the 1920s, specifically before the onset of the Great Depression. This period, known as the Roaring Twenties, was marked by significant economic growth and declining unemployment up until the stock market crash of 1929.
However, after 1929, during the Great Depression, the U.S. experienced severe economic downturns. The national unemployment rate rose dramatically, reaching approximately 25% between 1933 and 1935, and the Gross Domestic Product (GDP) shrank considerably. According to Keynesian economics, which emerged in response to the Great Depression, the lack of demand rather than the inability to produce goods led to declines in GDP and spikes in unemployment. The economic prosperity of the 1920s was not sustained into the following decade.