The rule of 70 is MOST useful in: A.identKeynesian economics promotes ideas that: A.government intervention can be destabilizing. B.the private sector is perfectly capable of regulating itself. C.the government can help a depressed economy via fiscal and monetary policies. D.the free market system will always prevail.ifying the sources of economic growth. B.identifying the causes of economic growth. C.estimating the productivity of labor. D.estimating the doubling time of real GDP for a given growth rate