D. People gave money to the war effort and received that money back with interest after the war.
Liberty Bonds were a way for the United States government to finance the cost of World War I. The government issued bonds that citizens could purchase to lend money to the government. The bonds were marketed as a way for Americans to support the war effort and to help pay for the cost of the war.
People who purchased the bonds were essentially lending money to the government, which would be paid back with interest after the war. The bonds were sold in different denominations, so people of all income levels could participate. The government used the money from the bonds to pay for the war effort, including weapons, ammunition, and supplies for soldiers.