Passage Summary: Being in a crowd makes people cranky and competitive. Because the world is getting more crowded, we should expect more violence and war in the future.

Conclusion: Increasing world population will lead to more frequent and severe instances of war and crime.

Reasoning: Overcrowding causes human aggression, as evidenced by the behavior of people in traffic or at sporting events.

Analysis: This is a 'Strengthen Except' question, meaning four options will support the conclusion and one will not. The argument makes a massive leap from 'people get annoyed in traffic' to 'global population growth causes war.' To strengthen this, we need to bridge the gap between minor social friction and major violent conflict. Look for the 'odd one out'—an answer that is either irrelevant to the link between density and aggression or one that suggests overcrowding doesn't necessarily lead to large-scale violence.