The number of Tundra swan in an arctic refuge has been steadily decreasing.

Cause of death: lead poisoning contained in the buckshot that hunters use to kill the swan.

Local authorities have banned hunting, and the number of hunters cited has since dropped dramatically,

yet the number of birds that continue to die each month from lead poisoning has not changed.

A. Migrating tundra swans fly through Idaho where they pick up various toxins from the silver mines there. (There is no mention of lead here. This cannot address the paradox.)

B. Those hunters who continue to defy the hunting ban do not, on average, shoot more birds than did those who hunted in the park before the ban. (this helps to address why the no is not increasing but does not address why the number is decreasing)

C. Park rangers have been unable to cite all of the the hunters that enter the park despite the ban. (Does not address the main concern. Makes one doubt doubt the premise.)

D. Most swans that have perished in the refuge have died as a result of ingesting pellets scattered about the ground, which introduce lead into their bloodstreams. (This explains why swans continue to die because of lead poisoning.)

E. Eventually, there will be so few swan left in the refuge that the overall number of swan dying each month will decrease. (This describes the future concern rather than address the issue.)

The answer to this would clarify from what other source were the birds exposed to lead poisoning. IMO, the answer is

The number of Tundra swan in an arctic refuge has been steadily dwindling. It has been determined that the majority of the birds have died from lead poisoning, which is contained in the buckshot that hunters use to kill the swan. Local authorities have responded by banning hunting, and the number of hunters cited has since dropped dramatically, yet the number of birds that continue to die each month from lead poisoning has not changed.

Which of the following, if true, best resolves the discrepancy above?

A. Migrating tundra swans fly through Idaho where they pick up various toxins from the silver mines there.
- This could be correct if the birds picked up lead from the silver mines, but this is not explicitly state.

B. Those hunters who continue to defy the hunting ban do not, on average, shoot more birds than did those who hunted in the park before the ban.
- this should only strengthen the argument and not explain for the gap. so this is ruled out.

C. Park rangers have been unable to cite all of the the hunters that enter the park despite the ban.
- this can explain partially, but not accounting for all hunters may not fully explain the gap

D. Most swans that have perished in the refuge have died as a result of ingesting pellets scattered about the ground, which introduce lead into their bloodstreams.
- this certainly explains the gap, hence correct answer. Is there a typo here ? is it 'scatter around the ground' ?

E. Eventually, there will be so few swan left in the refuge that the overall number of swan dying each month will decrease
- this does not explain the gap.

A. Migrating tundra swans fly through Idaho where they pick up various toxins from the silver mines there. - I don't know

B. Those hunters who continue to defy the hunting ban do not, on average, shoot more birds than did those who hunted in the park before the ban. - I don't know

C. Park rangers have been unable to cite all of the the hunters that enter the park despite the ban. - I don't know, maybe

D. Most swans that have perished in the refuge have died as a result of ingesting pellets scattered about the ground, which introduce lead into their bloodstreams.- I don't know

E. Eventually, there will be so few swan left in the refuge that the overall number of swan dying each month will decrease - I don't know

Interesting question. I think both A and D have strong and week spots. I chose A, but D makes sense to me as well.

A. Migrating tundra swans fly through Idaho where they pick up various toxins from the silver mines there. - It does not say lead, but lead might be included in "various toxins". Since these toxins remained at the same level, they might might be the cause of the deaths and therefore explain why the ban on hunting failed to impact the number of deaths from lead poisoning.

D. Most swans that have perished in the refuge have died as a result of ingesting pellets scattered about the ground, which introduce lead into their bloodstreams. - It makes sence, but I think there is a weak spot here: "yet the number of birds that continue to die each month from lead poisoning has not changed". Since they died by eating pellets from the ground, the diminished number of hunters should make the pellets on the ground decrease the more the swans ate them, making it less likely that the swans would eat it in the future and therefore decreasing the deaths over time.

[quote="souvik101990"]

The number of Tundra swan in an arctic refuge has been steadily dwindling. It has been determined that the majority of the birds have died from lead poisoning, which is contained in the buckshot that hunters use to kill the swan. Local authorities have responded by banning hunting, and the number of hunters cited has since dropped dramatically, yet the number of birds that continue to die each month from lead poisoning has not changed.

Which of the following, if true, best resolves the discrepancy above?

A. Migrating tundra swans fly through Idaho where they pick up various toxins from the silver mines there.

B. Those hunters who continue to defy the hunting ban do not, on average, shoot more birds than did those who hunted in the park before the ban.

C. Park rangers have been unable to cite all of the the hunters that enter the park despite the ban.

D. Most swans that have perished in the refuge have died as a result of ingesting pellets scattered about the ground, which introduce lead into their bloodstreams.

E. Eventually, there will be so few swan left in the refuge that the overall number of swan dying each month will decrease

[textarea]Day 24 Question of the Verbal Contest: Race Against the GMAT Club Timer

Left with A and D

A can be eliminated on the grounds that there is no mention of "Lead Poisoning". We can't assume toxins contain lead. So eliminate A

Answer - D

i feel it should be a, as it is clearly stated that the number of birds dying has not dwindled whereas the hunters have dwindled.
if number of hunters have dwindled then the number of pellets lying around will also dwindle leading to a conclusion that there is some outside force causing the deaths and that has to be the poisoning caused by silver mines.

Dear Puneetj88,
It talks of only the migrating Tundra birds and not all the Tundra birds. So this ans choice can be eliminated. If it would have not been for the word migrating, I would have picked this choice too.

Confused between 2 options, I marked the option, which was considering less of assumptions. Would love to have its OE. Took 45secs and finally a question I gave the answer in less than a min.

Applied POE method to arrive at the right answer. I found A & D to be the contenders.

Choice A though could appear to be tempting, it actually speaks about migrating tundra swans but not those in the refuge. It is also not clear in this choice whether lead is one of the various toxins they pick up while flying through Idaho.

Choice D resolves this confusion and clearly says the tundra swans that perished in the refuge ingested pellets that have introduced lead into their bloodstreams.

D might account for an initial increase in deaths i.e. initial number being the same as number of deaths when hunting was allowed. However, The stimulus states that there had been no change EACH subsequent month. If the question states they couldn't see the change in number the next month, D would have been the best answer out there.

Can you please explain me, where am going wrong here. daagh Sir, abhimahna

Official Explanation

Fact #1 – Arctic swan number rapidly declining

Fact #2 – Dying from lead poisoning from buckshot

Fact #3 – Authorities have banned hunting

Paradox: birds are continuing to decline at dramatic rate

(A) is focused on various toxins. The argument clearly says “the number of birds…die each month from lead poisoning”.

(B) only deepens the mystery since the hunters still entering the park aren’t killing more swan than previous hunters. If they were, then that could account for the fact that the number of swans continues to decrease.

(C) doesn’t quite resolve the paradox. It hints at the fact that there might be more hunters than previously thought still entering the park. But just how many? Is that number significant enough to account for the ongoing decrease in the swan’s numbers? Too many questions and no clear answer.

(D) resolves the paradox. The swan is not dying because it is being shot. It is dying because it is eating buckshot that has been lying on the ground all along. Unless, somebody cleans up all the buckshot pellet, the swan will continue to die, even if no more hunters enter the park.

(E) just tells us that the swan’s predicament is dire. It does provide a reason that the swan’s numbers continue to decline despite the ban on hunting.
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