External forces in the natural environment include A. the trend toward healthier lifestyles, which can shift spending toward exercise equipment and health clubs and away from alcohol and snack foods. B. air and/or water pollution, the depletion of irreplaceable natural resources, or inefficient energy/resource usage. C. interest rates, exchange rates, the inflation rate, the unemployment rate, the rate of economic growth, trade deficits or surpluses, savings rates, and per-capita domestic product. D. tax policy, fiscal policy, tariffs, the political climate, and the strength of institutions such as the federal banking system. E. slow growth in buyer demand.