Question

Which sequence of 20th-century Cold War

Answer 1

The proper sequence of 20th-century Cold War events would be "(4) adoption of the Marshall Plan → Cuban missile crisis → fall of the Berlin Wall," since the fall of the Berlin Wall effectively ended the official Cold War. 

Answer 2

Answer;
The sequence of 20th Century Cold War events in the correct chronological order is; 
Adoption of the Marshall Plan > Cuban Missile crisis > fall of the Berlin Wall.

Explanation;
Marshall plan was a programme of economic aid offered by the US to any European country. The plan was rejected outright by Stalin and any Eastern Bloc country considering accepting aid was reprimanded severely. Consequently the aid was given to the western European Countries.
The Cuban Missile crisis; a US spy plane was reported sighting the construction of a soviet nuclear missile base in Cuba. President Kennedy set up a naval blockade and demanded the removal of the missiles. War was averted when the Russians agreed to remove the weapons on 28th October.
The fall of Berlin Wall; in 1961 Berlin wall was built and borders sealed between East and West Germany. In 1989 the wall was torn down.