The philosophy of McCarthyism and the Truman Doctrine were similar in that B. Both argued that American security depended on the government's successful opposition to communism..
This was a movement in the late 1940s and early 1950s that aimed to remove communist influence in the U.S by brazenly attacking people for being communists without evidence.
They did this because they believed that the security of the U.S. would only be assured once communist influences were removed. This was also shared by the Truman Doctrine, albeit on an international scale.
In conclusion, option B is correct.
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