Final answer:
The federal government helped pay for the war effort during World War I by selling government bonds.
Step-by-step explanation:
One way that the federal government helped pay for the war effort during World War I was by selling government bonds. Bonds are essentially loans that individuals and businesses can purchase from the government. By selling bonds, the government could raise money to fund the war by promising to repay the bondholders with interest in the future. This allowed the government to finance the war without solely relying on taxes or borrowing from other countries.
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