Because it can be very reliable
Answer:
In 1947, President Harry S. Truman pledged that the United States would help any nation resist communism in order to prevent its spread. His policy of containment is known as the Truman Doctrine. The Truman Doctrine demonstrated that the United States would not return to isolationism after World War II, but rather take an active role in world affairs. To help rebuild after the war, the United States pledged $13 billion of aid to Europe in the Marshall Plan.
The United Stated had to contain communism from spreading through out Berlin, Korea, and Cuba.
Explanation:
The author who proposed the theory of "natural selection," which other people called "survival of the fittest" was named Charles Darwin. These two ideas are the founding basis of the theory of evolution.
Theodore Roosevelt and Woodrow Wilson, Theodore used his authority to protect wildlife and public’s lands by creating the United States Forest Service and establishing 150 national forests and more, During his presidency, Theodore protected around 230 million acres of public land. Woodrow Wilson on the other hand signed the “Organic Act” cresting the bureau responsible for protecting America’s 35 already existing national parks and monuments.
