You need to understand the main Idea in a story and the details to back it up and just understand it
Answer: Areas of defense in times of war
Explanation:
The except speaks of the potential of national unity in the United States being shattered as a result of a lack of a common enemy that the World Wars and Communism gave them.
The Fault lines in the excerpt refer to demarcations between opposing sides in the World Wars and in the Cold War that people then gathered behind to fight against their enemy. This made these lines become Areas of defense in essence that everyone came behind in solidarity to defeat their World War and Cold War enemies.
A. To establish the main points of the argument
