Passage Summary: Some people think that when big countries break up, trade suffers because of new tariffs. However, the economist argues this isn't true because small countries know they can't survive on their own.

Conclusion: Dividing large countries into smaller ones does not result in more trade barriers.

Reasoning: Small countries do not view themselves as being economically self-sufficient.

Analysis: This is a Sufficient Assumption question, so we are looking for a bridge that guarantees the conclusion is true. The economist's argument has a significant gap: it assumes that a country's psychological outlook—not seeing itself as self-sufficient—automatically dictates its trade policy. To make this argument bulletproof, we need an answer choice that explicitly connects the two, such as 'Any country that does not see itself as self-sufficient will not increase trade barriers.'