Passage Summary: Scientists found adult mammoth teeth on an island that are much smaller than usual. They conclude that the mammoths on that island were smaller than normal mammoths, assuming these teeth aren't just outliers.

Conclusion: Woolly mammoths on the island were, on average, smaller than those living in other locations.

Reasoning: Adult mammoth teeth found on the island are 25 percent smaller than adult mammoth teeth found elsewhere, and these teeth are assumed to be representative of the island's population.

Analysis: The argument makes a leap from the size of a specific body part (teeth) to the size of the entire animal. To make this conclusion 'properly drawn' or logically guaranteed, we need an assumption that links these two things together. The 'Gap' is the unstated rule that tooth size is a reliable indicator of overall body size in mammoths. Look for an answer that explicitly states that smaller teeth mean a smaller mammoth; without that link, the mammoths could have just had very small teeth in otherwise large bodies.