For as long as any state interacted with another in any politically significant manner, international relations were involved: relations between states. International relations encompass all sorts of interstate activities: trade, travel, war, peace, the environment, social interactions, religions, natural resources, diplomacy and many more exchanges of various types. The history of international relations began when two states interacted with one another. Four types of state systems evolved (the independent, hegemonic, imperial, and feudal). The correct answer is E.