Carrillo: Using the number of existing primate species, along with measures of the genetic diversity among these primates and among the extinct primate species, our statistical model strongly supports the developed around 81.5 million years ago.
Olson: Given that the oldest primate fossils discovered so far date back only 55 million years, your estimate of how long primate on is sheer speculation.
What this question is testing
Your task
Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.
Common trap
Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.
Winning move
Predict what a right answer must do, then test each choice against the conclusion-evidence gap.
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