Step 1: Event Summaries.
- Berlin Blockade (1948-1949): The Soviet Union's blockade of West Berlin triggered the Berlin Airlift, marking a major Cold War crisis.
- Berlin Wall Construction (1961): Erected to halt the flow of refugees from East to West Germany during the Cold War.
- Soviet Invasion of Czechoslovakia (1968): Soviet intervention to suppress the Prague Spring's political reforms.
- Communist China Joins the UN (1971): A pivotal change in global politics.
Step 2: Correct Order.
The chronological sequence is:
1. (D) Berlin Blockade (1948-1949)
2. (A) Berlin Wall is constructed (1961)
3. (C) Soviet invasion of Czechoslovakia (1968)
4. (B) Communist China joins the UN (1971)
Step 3: Solution.
The correct chronological order of these Cold War events is (2) D, A, C, B.