If Historians Can Explain the Factors That Caused a Violent

If historians can explain the factors that caused a violent international incident, why don't public policy makers learn from past mistakes and avoid such errors in the future, according to your textbook?

A) Nations are not always interested in avoiding such errors. They are more likely to be concerned with financial and political power and control.
B) Historians often don't agree on what caused an incident, only that it occurred. Therefore it's not always clear what the best course of action would be.
C) The future is too different from the past for any definitive lessons to be learned.
D) All of these are correct.