Critical Reasoning

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.

IMO B

is the oa A?

italian7745 wrote: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.

B

False cause. Author links dissimilarity of artifact found with place where Eurasians settled. But what if neither of these terms are connected? Its possible the Eurasians were travelers and got that artifact from a distant land but settled in North America. Ergo, the artifact does not define where the Eurasians are from. B attacks that assumption most successfully and weakens.

Source: Power Score GMAT CR Bible
OA: A

Can someone explain that why A is correct?

author concludes that since discovered mastodon had a different projectile, the settlers came from distant part of eurasia

A contradicts the statement saying that eurasian never used such mastodon.

The conclusion is that the first Eurasian settlers in NA came from a more distant part of Eurasia - the premises are that The projectiles found in the Mastadon were dissimilar to any from Eurasia closest to NA and the Eurasians did not settle until shortly before the Mastadon died.

In order to weaken the argument you need an answer that woudl show that the settlers didn't come from a more distant part of Eurasia eventhough these projectiles were dissimilar to those from near Eurasia.

A - weakens becuase it shows that the projectile isn't similar to any tribes - which means it can't be used to identify the settlers and thus, becuase it is the main support for the argument, the argument is weakened.

I totally disagree, according to me A is repeating what's already said in premise of the argument. How could this statement weaken the conclusion?

I think E is a very good answer since it destroys the reasoning used to reach the conlcusion.

I'm saying B as I think A repeats info from the passage. B says the people closest were nomadic so they moved around. Wouldn't that counter the assumption made?

IMHO it should be E, the conditions were so conducive that native human settlement was possible and thus no worries about migrants from Eurasia and their projectile!
Can someone please find out flaw in my reasoning? Why are we bound to Eurasian immigrants?
Thanks!

For a weaken question, we need to get to the core of the argument. More precisely, we need to have a strong understanding of the conclusion and its support. I find that putting the argument in my own words is quite helpful for achieving a strong understanding.

Here's the argument in my own words:
Premise: We've got a Mastodon with an arrowhead thing in it. The arrowhead is different from Russian or Chinese (the part of Eurasia close to North America) arrowheads.

Conclusion: Those settlers must have come Germany or France (the more distant part of Eurasia).

With this understanding, hopefully it jumps out that the conclusion makes some jumps. Couldn't the settlers have made a new arrowhead? Couldn't the Russians have had a similar arrowhead and we just never found one? Clearly this argument has made some assumptions, and in general, arguments are weakened by attacking those assumptions. We need to look for the answer choice that does just that.

A.[spoiler] So my arrow head doesn't look like any arrowheads anywhere! It doesn't look like Chinese or Russian arrowheads (as stated in the argument) AND it doesn't look like the German or French arrowheads! How can I then conclude that the people using it came from Germany or France? My argument sucks now. A weakens.

Note that 'A' does not simply restate the premise in the argument, which states that the arrowhead doesn't look like arrowheads from nearby Eurasians. 'A' says the arrowhead doesn't look like anybody's arrowheads![/spoiler]

B.[spoiler] Huh, turns out the Russians and Chinese were still wandering around during the ice age... wouldn't that make it more likely that the settlers came from one of those places and not Germany or France as is argued? Ya, I think a case could be made for that. However, the author's case is focused on the 'arrowhead similarity' issue. We need to attack that line of reasoning, and B doesn't do that. Wrong.[/spoiler]

C.[spoiler] There was a bear in the same area with the same kind of arrowhead in it. Cool! This seems to reinforce the fact that my premises are solid... it definitely doesn't weaken. Wrong.[/spoiler]

D.[spoiler] Oh look at that, other stuff found in North America from that period looks like stuff from Germany and France! Wait hold on, this is supporting my argument. Wrong.[/spoiler]

E.[spoiler] So apparently North America was a better place to live than China or Russia at the time. So wouldn't those Chinese and Russians want to head on over? Wouldn't that weaken the argument that the settlers were from France or Germany? This is similar to B. While a case could be made here, it doesn't touch the argument that the author has made about arrowhead similarity. We need something that weakens the author's reasoning about arrowhead similarities. Wrong.

Whats_in_the_store: Good conditions or poor conditions, really why are we bound to the Eurasian immigrants! I agree! This is another assumption our author has made. He assumed there weren't already some folks hanging out from somewhere else entirely! However, saying that the climatic conditions were more favorable in North America than in nearby Eurasia at that time doesn't make it any more or less likely that any one particular group of people was hanging out there.[/spoiler]

Answer:[spoiler]A
To summarize, put the argument in your own words and focus on the conclusion and given support for that conclusion. For a weaken question, we must attack the assumptions made by the author. Be wary of opposite answers and answers that can be shown to put the conclusion in question but don't attack the reasoning given.[/spoiler]