During the Cold War, Country I, with its democratic government in Western Europe, would likely have joined the North Atlantic Treaty Organization (NATO), which was a military alliance of Western democratic nations. Country II, with its communist government in Eastern Europe, would likely have joined the Warsaw Pact, which was a military alliance of communist nations.
Therefore, the correct response is: Country I would have joined the North Atlantic Treaty Organization, and Country II would have joined the Warsaw Pact.