B. The United States built a series of defensive fortifications in the 1950's called the Iron Curtain.
The Iron Curtain referred to the satellite nations that Russia controlled that acted as buffer between Western Europe and Russia.
Innovations in technology radically change military budget allocation from focusing on soldiers development into budget plan that focus on development of weapons and war vehicles.
In the late nineteenth century, industrialized nations able to produce high quality weapons in large quantity due to the industrial revolution. Since those weapons able to eliminate enemies in larger numbers, all countries start to see that focusing their budget for those weapons were far more beneficial.
The correct answer is A. Formal qualifications are outlined in the Constitution
Those qualifications are that you must be a citizen, be of the appropriate age, and must live in the country for which he/she is applying to the senate position.