Is there any correct and significant answer for why and what country started the Cold War?

The answer to this question is a matter of perspective. The Cold War came about due to the rivalry that emerged between the United States and the Soviet Union in the immediate aftermath of World War II. The biggest issue involved postwar Europe. When the Soviet Union essentially set up Soviet-style communist regimes in Eastern Europe, beginning with Poland, the United States saw it as aggression on par with that perpetrated by Adolf Hitler leading...

The answer to this question is a matter of perspective. The Cold War came about due to the rivalry that emerged between the United States and the Soviet Union in the immediate aftermath of World War II. The biggest issue involved postwar Europe. When the Soviet Union essentially set up Soviet-style communist regimes in Eastern Europe, beginning with Poland, the United States saw it as aggression on par with that perpetrated by Adolf Hitler leading up to World War II. From a Soviet perspective, however, it was a necessary move to establish a buffer zone between the Russian frontier and Western Europe, especially Germany. The Soviets had suffered over 27 million deaths during World War II, and they wanted to secure their borders. Similarly, the Soviets viewed American attempts to establish a pro-western government in Germany, as well as the flooding of Western Europe with American loans and economic assistance as capitalist aggression, and feared they ultimately wanted to destabilize the Soviet regime itself. Perhaps it is best to simply say that the Cold War developed because the two major superpowers who were left standing at the end of World War II had irreconcilable interests which led them into a series of political (and nearly military) conflicts.