LSAT-0110-4-20

20. Archaeologist: A skeleton of a North American mastodon that became extinct at the peak of the Ice Age was recently discovered. It contains a human-made projectile dissimilar to any found in that part of Eurasia closest to North America. Thus, since Eurasians did not settle in North America until shortly before the peak of the Ice Age, the first Eurasian settlers in North America probably came from a more distant part of Eurasia.
Which one of the following, if true, most seriously weakens the archaeologist’s argument?
(A) The projectile found in the mastodon does not resemble any that were used in Eurasia before or during the Ice Age.
(B) The people who occupied the Eurasian area closest to North America remained nomadic throughout the Ice Age.
(C) The skeleton of a bear from the same place and time as the mastodon skeleton contains a similar projectile.
(D) Other North American artifacts from the peak of the Ice Age are similar to ones from the same time found in more distant parts of Eurasia.
(E) Climatic conditions in North America just before the Ice Age were more conducive to human habitation than were those in the part of Eurasia closest to North America at that time.

请教本题思路.

A skeleton of mastodon was discovered in North American;  The skelton contains a human-mmade projectile. it is dissimilar to those found in the part of Eurasia closest to North America (NA). Since Eurasians began to settle in NA shortly before the peak, the first Eurasians who came to settle in NA came from a more distant part of Eurasia, rather than the part closest to the NA.

the basic threat of reasoning is: the projectile found in NA is different from those in the part of Eurasia closest to NA, therefore, the first Eurasian settlers in NA did not came from that part of Eurasia. The underlying assumption here is: the projectile is Eurasian (brought to NA by Eurasian settlers or something like that)

Answer:A

it weakens the argument by showing that the projectile might have nothing to do with Eurasian at all.