Answer:
D. Created a strong alliance between the US and Western European countries.
Explanation:
The Marshall Plan was a way for the US to provide aid to Western Europe in 1948 after the conclusion of WW2. WW2 left Europe in ruins, while the US, due to its geopolitical location, was left relatively unscathed on its home front. Through this plan, the US was ultimately able to provide billions of dollars in aid to Western Europe.
On the other hand, NATO stands for the North Atlantic Treaty Organization, and it was a mutual defense pact formed by the US and its allies. NATO included the US, Canada, and 10 Western European countries. With NATO, these countries essentially pledged to defend each other under attack and to collectively work towards their mutual safety and security.
Therefore, both NATO and the Marshall Plan strengthened the US's ties to Western Europe, making the answer D correct.
We can also analyze the other answer choices to see why they're incorrect:
Option A is incorrect because the Marshall Plan has nothing to do with the Korean War, it was simply a way to provide aid to Europe. Moreover, the Korean War was primarily between North Korea and South Korea, as a proxy war during the Cold War. Not all NATO countries were involved, and the US wasn't defending their own security, rather they were fighting Communism in Asia.
Option B is incorrect because the Marshall Plan provided huge sums of economic aid that only made rebuilding Europe easier.
Option C is incorrect because NATO only increased tensions. Not only did NATO mean that the US could station weapons in its member states (meaning weapons in closer proximity to the Soviet Union's territory) but it also made tensions impossible to deny. The Soviet Union and its allies would respond in 1955 with their own pact known as the Warsaw Treaty Organization.
