In polluted environments, dolphins gradually accumulated toxins in the

I like A, but can't the newly born dolphins die simply because of unavailability of other nutrients in the milk or because of mommy to take care? Or is this thinking too much? However, the best answer seems to be A

I dont want to think much I go with A.

whatthehell: A says that if the mother is not there then 'survival' rate is higher. Not the mortality rate. So we dont have to think about the reason for the calves being dead.

Hi,

As the conclusion states that poisoned mother milk cause high motality rate of dolphins calves.

Keeping this in mind. How can we eliminate the option C,which states that " Among dolphin calves born in the area along Florida’s Gulf Coast, the mortality rate is highest among those with living siblings" Doesn't that implies that living with siblings means ,there would be presence of mother here,and mother would be feeding poisoned milk.

isn't it?

Please help me where I'm wrong?


Thanks

Hi Nitin

C, if anything, could be considered a weakener. The question asks you to strengthen the argument that the unusually high mortality rate among dolphin calves in the industrially contaminated waters along Florida’s Gulf Coast is probably the result of their being poisoned by their mother’s milk.

But option C tells us that mortality rate is highest for these calves who have living siblings. This means that both the calf (which subsequently died) and its living siblings could have had the same mother’s milk but while its siblings survived, it died. So it indicates that poisoning from mother’s milk is not the likely cause here for the high mortality rate of calves.
Hope that clarifies your doubts

Regards
Prashant

Conclusion: Mothers pass toxic to their calf through their milk.

A. The survival rate of firstborn dolphin calves in the area along Florida’s Gulf Coast is highest for those whose mothers were killed before they were weaned - Supports the conclusion.

B. The rate at which adult dolphins living in the waters along Florida’s Gulf Coast accumulate toxins is no higher than that of adult dolphins in comparably polluted waters elsewhere - Out of Scope. It is neutral to the argument.

C. Among dolphin calves born in the area along Florida’s Gulf Coast, the mortality rate is highest among those with living siblings.
Not supporting the arguments, presents an alternate clause - Weakens the argument.

D. As dolphins age, they accumulate toxins from the environment more slowly than when they were young.
Not supporting the arguments, presents an alternate clause - Weakens the argument.

E. Dolphins, like other marine mammals, have a higher proportion of body fat than do most land mammals.
Out of scope.

x-toxic milk
y-high mortality rate
x causes y
to strengthen
-only x can cause y
- no x no y
so A ,which says NO X NO Y

Official Answer Explanation
Reasoning Given the facts stated, what would make the dolphin calf deaths more likely to have resulted from toxins in their mothers’ milk? The dolphins live in a polluted environment. Therefore, the mother dolphins are accumulating toxins in their body fat. Most of the toxins in a mother dolphin pass through her milk into her nursing calf. Since dolphin calves are much smaller than their mothers, the calves are especially vulnerable to the toxins. The high mortality rate among the calves is more likely to have resulted from the toxins in the milk if calves who drink more milk have been more likely to die.

A Correct. Calves whose mothers died before weaning would have drunk less toxic milk than other calves did, on average.
B If dolphins along the Florida’s Gulf Coast accumulated toxins at no higher a rate than elsewhere, then their milk would contain no more toxins than elsewhere and thus would not be especially likely to cause an unusually high mortality rate.
C Since dolphin calves presumably consume milk from the same mother as their siblings do, this would suggest that some factor other than the milk caused the high mortality rate.
D If the calves accumulate toxins more quickly from the environment than their mothers do, the high mortality might have resulted mainly from toxins in the environment, not from those in the milk.
E The argument says nothing about other mammal species, therefore this information is irrelevant.

VeritasKarishma - is my analysis on B correct per your view ?

B seems to me almost an answer to an assumption question (not a strengthener question)

If the question was instead asking "In order for the conclusion to be true, what assumption is the author making" -- would B be accurate ?

Let ma'm confirm your answer.

I add my thought:
No, B can not be an assumption. How does rate of accumulation depends on total fat accumulated. It maybe quite possible that dolphins in one are accumulate slower than those of other area. It has no influence on our conclusion.

In similar lines, assumption could be:
dolphins bodies don't behave differently in Florida water as compared in other areas. We want to highlight that Florida pollution water is similar to other area water or dolphins are not different than dolphins in other areas. Whatever happens, it happens because of pollution in water.
basically , if X-->Y we are saying that Z doesn't lead to Y. Whatever is happening to Y, it is happening because of X.

Hope it helps.

Dolphins accumulate toxins in their body fat, and the larger the dolphin the more accumulated toxin it can tolerate. Nearly 80 percent of the toxins a female dolphin has accumulated pass into the fat-rich milk her nursing calf ingests.
There is unusually high mortality rate among dolphin calves in the industrially contaminated waters along Florida’s Gulf Coast.

Conclusion: It is probably the result of their being poisoned by their mother’s milk.

We need to strengthen that the reason for unusual mortality rate is mother's milk.

(A) The survival rate of firstborn dolphin calves in the area along Florida’s Gulf Coast is highest for those whose mothers were killed before they were weaned.

Correct. The infants survived better if they were fed on mother's milk for lesser time. Then it does seem more likely that they are being poisoned by mother's milk.

(B) The rate at which adult dolphins living in the waters along Florida’s Gulf Coast accumulate toxins is no higher than that of adult dolphins in comparably polluted waters elsewhere.

Irrelevant. Even if the rate of toxin accumulation is the same, we don't know what is the survival rate of calves in other polluted waters. Do they also see unusual mortality rate? We don't know. If they don't see unusual mortality rates then it seems that mother's milk is not responsible (that will weaken our conclusion). It they see unusual mortality rates too, then it doesn't mean that mother's milk is responsible. It could be the polluted waters that are directly making calves sick or some other such reason.

(C) Among dolphin calves born in the area along Florida’s Gulf Coast, the mortality rate is highest among those with living siblings.

We can't say what this means for our conclusion. If the calves have older siblings, they should get less toxins (since much of stored toxins could have already been passed on to the older sibling). Also, if a sibling is alive but this calf dies, mother's milk may not be the reason.

(D) As dolphins age, they accumulate toxins from the environment more slowly than when they were young.

Irrelevant. We are wondering why the calves' mortality has suddenly increased.

(E) Dolphins, like other marine mammals, have a higher proportion of body fat than do most land mammals.

No connect to mother's milk.

Answer (A)

jabhatta2

An assumption is just a special kind of strengthener. All strengtheners (including assumptions) increase the probability of the conclusion but an assumption has the added characteristic of being necessary for the conclusion to hold.

Option (B) is not a strengthener so it can certainly not be an assumption.

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