Why Do We Need to Study Totalitarianism Since the Soviet

Why do we need to study totalitarianism since the Soviet Union is gone?

A) It can be any nation's next government, if there is great poverty, injustice, turmoil, or violence.
B) It can evolve any nation into an ideal society in our world.
C) We can learn from its failures to make the next regime better.
D) It is the most popular ideology in the world, currently.
E) None of the above is correct.