Answer:
By conducting to plant more trees and reducing the use of gas that emitting Co2 that cause to rise the temperature.
I would say that the US and the Soviet Union at the end of WWII withdrew their troops as soon as a demilitarized zone was created. Also, I am sure they would require a peace treaty to be signed with Germany before withdrawing troops.
Reason a is the correct one, as the european union has nothing to do with protection from invasions and Germany reunified many years ago.
It really depends on which war the question is referring to, but if it's referring to WWII the answer would be true.
