Final answer:
The 1929 stock market crash marked the end of the 1920s and the start of the Great Depression.
Step-by-step explanation:
The major event that marked the end of the roaring 1920s and the start of the Great Depression was b. The 1929 stock market crash. On October 29, 1929, also known as Black Tuesday, the stock market experienced a sharp decline, leading to the loss of billions of dollars and triggering a widespread economic crisis. This event shattered the optimism and prosperity of the 1920s and set the stage for the prolonged period of economic hardship and financial turmoil known as the Great Depression.
Learn more about The impact of the stock market crash on the economy and the onset of the Great Depression