Passage Summary: We found more types of frogs and salamanders than we thought we had, so environmentalists must be wrong about pollution killing them.

Conclusion: The environmentalists' claim that pollution is killing off many amphibian species every year is definitely incorrect.

Reasoning: Biologists have recently discovered that there are many more species of amphibians in existence than was previously thought.

Analysis: This argument suffers from a classic confusion between discovery and existence. Finding new species (an increase in our knowledge) does not mean that species aren't being lost (a decrease in the actual population). It's a bit like finding a twenty-dollar bill in an old coat and claiming you aren't losing money, even though your wallet has a hole in it. Look for an answer that points out that discovering more species is entirely compatible with many species being eliminated by pollution.