What phrase describes defense agreements among nations?

• A. Alliances
• B. Treaties
• C. Coalitions
• D. Alliance systems

Answer: (D)

When we talk about defense agreements among nations, the idea is a network of formal commitments that bind states to come to each other’s aid. The phrase alliance systems captures that broad, interconnected pattern, not just a single pact. It signals an ongoing security framework where multiple countries align with and support one another, creating a stable network of obligations. A single alliance refers to one specific agreement, a treaty is the legal instrument that could cover various topics, and a coalition is usually a temporary, task-specific group. So the term alliance systems best describes the idea of multiple defense agreements forming a connected security structure.