I think the answer is the 3rd one. Hope this helps!
Answer:
Explanation:
The Navajo they were used in WWII for using code words and it was the only code during the time that was never broken by the enemy because they never understood the meaning or background of the words set out between the Navajo and US.
Its A. The space race was during the cold war so Nuclear Threat was number one was very important to the US to keep under control, however when the Russians launched Sputnik One the race to space stated. Some believe it was to push the other into submission so no nuclear war would not start. The only reason the Cold war isn't still ongoing is because of M.A.D. At one point there was even a treaty to make the two space programs one and end the cold war permanently, however, that never came to pass.