The stimulus presents an argument, as follows: P: A skeleton of a mastodon that became extinct at the peak of the Ice Age was recently discovered. P: This skeleton contains a human-made projectile that is NOT like any found in that part of Eurasia closest to N. America. P: Eurasians did not settle in N. America until shortly before the peak of the Ice Age. C: Therefore, the first Eurasian settlers in N. America probably came from a more distant part of Eurasia.
All right. This stimulus fixates on humans from only one source place: Eurasia. Answer choice (A) weakens the argument. If it is true that the projectile found in the mastodon is unlike any used ANYWHERE in Eurasia either before or during the Ice Age, then the argument in the stimulus is weakened - because the evidence on which it rests (premise #2) does not actually support the conclusion. Put differently, if (A) is true, Eurasia is off the table in the premises, and so a conclusion about Eurasia is fundamentally weakened.
