Question

I need some help, can anyone tell me what the correct answer is and why?
Which explains the effect of demobilization following WWI on the economy?
The global economy soared, which created stiff competition between U.S. and foreign industries.
The demand for war materials lessened, which weakened the global economy.
The global economy boomed as countries demanded industrial products to rebuild their territory.
The demand for industrial workers increased, which benefitted the soldiers returning from war.