Passage Summary: Tall dams are more likely to break, and most dams in the world are tall. However, every recent dam failure has happened to a short dam.

Reasoning: Higher dams are theoretically more vulnerable to collapse and represent the majority of arch dams, yet only shorter dams have actually collapsed recently.

Analysis: We are faced with a classic discrepancy between theoretical risk and actual outcomes. If height increases risk and tall dams are the majority, we would expect them to fail more often, yet the opposite is happening. To resolve this, we need a factor that makes tall dams safer in practice or short dams more vulnerable despite their lower height. Look for an answer that introduces a variable like stricter engineering standards for tall dams or the fact that tall dams are generally newer and better maintained.