The statement that best describes why the aggregate demand shifted left between the period is because customer income dropped severely.
First and Foremost, the period depicted in the question is known as Great Depression which is when the U.S. experienced the worst economic meltdown.
During this period, millions of workers lots their jobs because business and banks collapse because of the economic meltdown.
Now, the graph in question shows that aggregate demand move to the left and means that the total consumer spending has declines.
The decline in consumer spending is expected because there is little or no income because of the loss of job, inflation that happen during the great depression.
Hence, the Option C is correct because its best describes the reason aggregate demand move to left.
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