Answer:
A. Both wars grew in scale when the United States intervened to stop communist groups from taking control of the government.
Step-by-step explanation:
The Korean War and the Vietnam War were similar in that they both began as a Cold War conflict between communism and capitalism. This is the reason why the wars interested several countries, particularly the United States. These wars are considered "proxy wars" because the real conflict beneath the surface was between the Soviet Union and the United States. When the United States intervened in order to fight against the communists, both wars grew in scale, becoming a lot more deadly and a lot more difficult to solve.