What is the main reason the U.S. economy grew so rapidly during the Keynesian Era? a.Corporate tax cuts increased business hiring, lowering unemployment and leading to high consumption and investment b.Decreased income-support policies for the unemployed increased their incentive to work, lowering unemployment and leading to high consumption and investment c.Price stability policies lowered inflation, providing for increased certainty about the future, lowering unemployment and leading to high consumption and investment d.Wage support and full employment policies, along with powerful unions, increased incomes for a majority of the population, lowering unemployment and leading to high consumption and investment