Answer: C. Alliances should be maintained as long as they are useful.
Explanation:
This kind of idea is most similar to Realpolitik ideas that were coined by Niccolo Machiavelli because they are standing for power, pragmatism and realism concept in the politics and society.
This kind of idea is considering practical government and it is best going with the answer C) because they are both considering alliances that should be useful for the people who are in the society and government.