Summary
After the Cold War, international relations between allied nations became more difficult. Leaders of previously allied nations were required conduct tactful economic negotiations for the purpose of not triggering tensions that were previously overlooked.
Strongly Supported Conclusions
Bonds between nations are strengthened by a common enemy, and this bond enables nations to overlook otherwise problematic economic tensions.
A
International economic competition is a greater cause of tension than is international military competition.
This answer is unsupported. We don’t know from the stimulus whether military competition was a cause of tension between nations.
B
Bonds between allies are stronger when they derive from fear of a common enemy than when they derive from common economic goals.
This answer is unsupported. We don’t know anything about bonds derived from common economic goals from the stimulus.
C
When there is a military commitment between countries, fundamental agreement between them on economic matters is more easily reached.
This answer is unsupported. We don’t know from the stimulus whether economic agreement was more easily reached between allied nations. We only know that these bonds led nations to overlook economic tensions.
D
Economic matters are considered unimportant during periods of actual or threatened war.
This answer is unsupported. We don’t know whether economic matters were considered unimportant. We only know that economic tensions may have been overlooked.
E
A common enemy contributes to a strengthened bond between nations, enabling them to ignore economic tensions that would otherwise be problematic.
This answer is strongly supported. This principle explains why, after the Cold War, previously allied nations were required to conduct tactful economic negotiations. The nations’ allegiance allowed them to overlook economic tensions between themselves.
Summary
Every person who participated in the town’s annual spring cleanup received a community recognition certificate. However, there are some spring cleanup participants who are not active in the town’s artistic circles because the spring cleanup took place at the same time as the downtown arts fair.
Notable Valid Inferences
Some people who received community recognition certificates are not active in the town’s artistic circles.
A
Some of the persons who are active in the town’s artistic circles received community recognition certificates.
Could be false. As shown in our diagram, our conditions are limited to persons who are not active in the town’s artistic circles. We cannot infer anything about people who are active in the town’s artistic circles.
B
Not all of those who received community recognition certificates are active in the town’s artistic circles.
Must be true. As shown below, we can always infer a “some” statement between conditions that branch off from a sufficient condition in common. 
C
No participants in the downtown arts fair received community recognition certificates.
Could be false. We know that the arts fair and the spring cleanup took place at the same time, but we cannot assume that it is impossible for a person to participate in both events.
D
No person who received a community recognition certificate has not participated in the spring cleanup.
Could be false. This answer choice confuses sufficiency for necessity. It is possible that a person received a recognition certificate without participating in the cleanup. A necessary condition can always occur without the sufficient condition.
E
Persons who are active in the town’s artistic circles are not concerned with the town’s environment.
Could be false. As shown on our diagram, we have no conditions relevant to a person’s concern with the environment. Moreover, we cannot assume that people who didn’t participate in the cleanup are not concerned with the environment.