Passage Summary: Scientists found tiny plant bits on old ape teeth and decided that because they only found a few types of plants there, those must have been the only things the apes ate.

Conclusion: The extinct great ape species ate only the specific plant species whose phytoliths were found on their fossilized teeth.

Reasoning: Microscopic plant remains from only a few specific plant types were discovered on the fossilized teeth of these apes.

Analysis: The argument makes a massive leap from 'what was preserved' to 'what was eaten.' It assumes that if an ape ate a plant, that plant must have left behind phytoliths that survived for millions of years. Look for an answer that addresses this preservation gap—specifically, that other plants the apes might have eaten wouldn't have left different phytoliths or that these are the only ones that could have existed. The argument fails if it turns out that many plants simply don't leave these microscopic remains behind.