Final answer:
West Germany used a capitalist economic system for post-WWII recovery, greatly aided by the U.S. through the Marshall Plan, leading to significant economic growth.
Step-by-step explanation:
The economic system that West Germany primarily used to aid in its post-World War II recovery was capitalism. This was supported by the massive influx of aid under the Marshall Plan, by which the United States provided financial support and assistance to rebuild the economies of European nations, including West Germany. The adoption of this economic system and the rebuilding efforts resulted in significant industrial recovery and economic growth over the following decades, turning West Germany into an economic powerhouse by the 1970s.