The phenomenon in which behaviors that are conditioned only sometimes, thus causing them to be more resistant to extinction, is known as PARTIAL REINFORCEMENT.
Answer:
D it has increased diversity including diverse languages and values
NATO is still relevant today because its growth makes it virtually impossible for member countries to be attacked. The correct option among all the options that are given in the question is the last option. IT can be said that with each passing day the importance of NATO is increasing. Unitedly it stands on a stronger ground also for continuing peace.