Final answer:
Poststructuralists disagree with realists on the point that the state is the sole actor in international politics, challenging the realist notion with the view that multiple actors influence world politics.
Step-by-step explanation:
​Poststructuralists in international relations theory agree with realists that the state plays a central role in world politics. However, they diverge from realists on several key points. Realists view states as the primary actors in a zero-sum game, where power and gain are finite and what one state secures, another loses. Realists also argue that states are unitary actors that formulate policies based on their individual interests and see security as the utmost concern. In contrast, poststructuralists challenge these notions by arguing that there are multiple actors in international politics, power dynamics are complex and not solely a zero-sum game, states are not always cohesive unitary actors, and there are other concerns beyond security that influence state behavior.
Given the choices provided: A) The state is the sole actor in international politics, B) Power is a zero-sum game, C) States are unitary actors, D) Security is the primary concern in international relations; the disagreement between poststructuralists and realists indicated in the question pertains to Option A, that the state is the sole actor in international politics. Poststructuralists argue that this view is too limited and overlooks the diverse range of actors and influences at play in international relations.