there is a lot of confusion on this thread.

"wean" means to gradually stop drinking the mother's milk.

the argument in the passage is that dolphin calves are dying because their mother's milk is poisoned.

(a) says the survival rate of firstborn calves is higher if the mother dies before the calf is weaned. in other words, the calf is more likely to survive if the mother dies during the calf's milk-drinking period. this strengthens the argument, because if calves are dying from poisoned milk, the less milk they drink, the more likely they are to survive. fitzgerald's explanation is correct.

(b) this is irrelevant to the argument, because it concerns adult dolphins in florida and adult dolphins elsewhere -- not baby dolphins.

(c) this actually weakens the argument, because it says calves who have living siblings are more likely to die. if the reason for the death was the poisoned mother's milk, the siblings would also be dead.

(d) this also weakens the argument, because if young dolphins accumulate toxins from the environment more quickly than do older dolphins, the young dolphins may be dying of toxins from their environment, rather than from their mother's poisoned milk.

(e) also irrelevant, because dolphin body fat percentage affects all dolphins -- young and old.

(A) seems to be right.

'A' properly links mother - mortality rate - weaning !

Choose A !

This is a Strengthening question. The conclusion states that mortality rate among dohin calves is due to them being poisoned by their mother (and not the contaminated water). What supports this?

A) dolphins that don't wean on their mothers milk (which is poisoned) have a higher survival rate. CORRECT- if they did, they would die according to the prompt.
b) we're talkin about babies, not adults.
c) siblings have nothing to do with calves dying b/c of their mother's poisoned milk.
d) nothing to do with mortality rate from mother's poisoned milk.
e) unrelated...

Answer is A.

IMO A.....Thought of writing the expl, but all the members have done well for this post

A it is..

Good Question, A

maihuna wrote:In polluted environments, dolphins gradually accumulated 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. Therefore, 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.
Which of the following, if true, most strengthens the argument?
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.
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.
C. Among dolphin calves born in the area along Florida's Gulf Coast, the
mortality rate is highest among those with living siblings.
D. As dolphins age, they accumulate toxins from the environment more slowly
than when they were young.
E. Dolphins, like other marine mammals, have a higher proportion of body fat
than do most land mammals.

Choice "A" provides a basis on which to suspect that dolphin mothers are the reason for high calf mortality. The fact that calves who do not have mothers have a higher survival rate supports the original conclusion.

In polluted environments, dolphins gradually accumulated 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. Therefore, 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.
Which of the following, if true, most strengthens the argument?
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.
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.
C. Among dolphin calves born in the area along Florida's Gulf Coast, the
mortality rate is highest among those with living siblings.
D. As dolphins age, they accumulate toxins from the environment more slowly
than when they were young.
E. Dolphins, like other marine mammals, have a higher proportion of body fat
than do most land mammals.

I think "A".

Answer should be A.

Answer should be A.

maihuna wrote:In polluted environments, dolphins gradually accumulated 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. Therefore, 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.
Which of the following, if true, most strengthens the argument?
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.
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.
C. Among dolphin calves born in the area along Florida's Gulf Coast, the
mortality rate is highest among those with living siblings.
D. As dolphins age, they accumulate toxins from the environment more slowly
than when they were young.
E. Dolphins, like other marine mammals, have a higher proportion of body fat
than do most land mammals.
[spoiler]Answer:A[/spoiler]

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Hi I know everyone has given his/her explanations already. But I just wanted to add my 2 cents on this question:

Firstly, check out this article, https://www.beatthegmat.com/mba/2015/06/ ... ning-score , It is brilliantly written and focuses on EXACTLY what we should try doing each time on a CR Question

Ok, so this is a strengthen question. The flow of the argument is as follows:
Larger the dolphin ---> More toxin it can tolerate --->for the Females, >80% of the toxins move into the milk ---> which the calves drink ---> Hence, mortality rate among st calves is high (conclusion)

Lets go by elimination from below:
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. Okay, dont quite know the meaning of 'weaned'. So lets keep this in, Dont "throw out" choices that easily. be pro-active

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. Hmm, this seems to COMPARE the RATE at which toxins are accumulated. Not important!

C. Among dolphin calves born in the area along Florida's Gulf Coast, the
mortality rate is highest among those with living siblings. Comparison again! this time b/w siblings of calves. Not Important! Does NOTHING to strengthen.

D. As dolphins age, they accumulate toxins from the environment more slowly
than when they were young. Tricky. So this says, dolphins accumulate more slowly as they age. If it were true, then calves would accumulate toxins sooner/faster and hence die. Okay, this sort of strengthens. But what does it strengthen? It strengthens the fact that calves DO accumulate and react to toxins. But WHAT IS THE SOURCE of the toxins? Not mentioned. So this is an OK sort of option.

E. Dolphins, like other marine mammals, have a higher proportion of body fat
than do most land mammals. Comparison of body fat. NOT important.

Now compare A and D:

A says ---> 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. Now despite NOT knowing the meaning of 'weaned'. Lets try to understand this: The survival rate of firstborn dolphins is high ---> when? ---> their mothers (who carried the toxins) were killed before they were 'weaned'. This as an assumption can be stated as: before they probably consumed the threshold amount of toxins, their mothers were killed. So these calves survived. Now it isn't imp to know meaning of every word. If one can catch the intended meaning (SC?? heehee ) of the sentence then its fine

D just talks about the rate at which toxins are accumulated, not the source.

Comparing both, A seems stronger. So have faith and choose A

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