The answer to the question is A
The war cost more than 2 million lives and ruined the economy of Korea for twenty years. It also had implications for a wider conflict, the Cold War. The main protagonists of that political, economic, military and ideological contest, the Soviet Union And the United States of America, intervened in the Korean War. The Soviet Union and its ally China backed North Korea, while the United States gathered an alliance under the auspices of the United Nations (UN) to support the south
( I don't know if this is 100% correct but...)
Answer:
After the Pax Romana, came a period in which the Roman Empire nearly collapsed under the combined pressures of invasion, civil war, plague, and economic depression.
