Which of the following is not a characteristic of the state system that existed from World War II until the early 1990s?

a. It was based on a balance of power model.
b. It existed fundamentally unchanged, with few new additions to the numbers or types of international
actors.
c. It replaced a failed effort to create a collective security system between World Wars
I and II.
d. It had many fundamental flaws, but succeeded in keeping peace between major
actors.

b