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C
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Difficulty:
55%
(hard)
Question Stats:
64% (01:50) correct
36%
(02:20)
wrong
based on 13350
sessions
History
Date
Time
Result
Not Attempted Yet
Between 1980 and 2000 the sea otter population of the Aleutian Islands declined precipitously. There were no signs of disease or malnutrition, so there was probably an increase in the number of otters being eaten by predators. Orcas will eat otters when seals, their normal prey, are unavailable, and the Aleutian Islands seal population declined dramatically in the 1980s. Therefore, orcas were most likely the immediate cause of the otter population decline.
Which of the following, if true, most strengthens the argument‘?
(A) The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined.
(B) Seals do not eat sea otters, nor do they compete with sea otters for food.
(C) Most of the surviving sea otters live in a bay that is inaccessible to orcas.
(D) The population of orcas in the Aleutian Islands has declined since the 1980s.
(E) An increase in commercial fishing near the Aleutian Islands in the 1980s caused a slight decline in the population of the fish that seals use for food.
Which of the following, if true, most strengthens the argument‘?
(A) The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined.
(B) Seals do not eat sea otters, nor do they compete with sea otters for food.
(C) Most of the surviving sea otters live in a bay that is inaccessible to orcas.
(D) The population of orcas in the Aleutian Islands has declined since the 1980s.
(E) An increase in commercial fishing near the Aleutian Islands in the 1980s caused a slight decline in the population of the fish that seals use for food.
Sea Otter Population
Step 1: Identify the Question
The words if true and most strengthen indicate that this is a Strengthen the Argument question.
Step 2: Deconstruct the Argument
80 to 00: Otter pop ¯
No disease, maln, so prob predators
Orcas eat seals, but seals ¯
© Orcas ate otters à pop ¯
Step 3: Pause and State the Goal
On Strengthen questions, the correct answer is a piece of information that makes the conclusion more likely to be true. What additional evidence could support the idea that the orcas were the cause of the declining otter population?
Step 4: Work from Wrong to Right
(A) An increase in the sea urchin population would be a logical result of a decline in sea otters because there were fewer otters eating the sea urchins. This information does not clarify whether orcas were the cause of the decline in otters.
(B) The argument states that the seal population declined at the same time as the sea otter population. Thus, competition for food with or predation by seals were unlikely to have been possible explanations for the decline in sea otters. Removing these as possible causes, then, does not actually strengthen the argument.
(C) CORRECT. The orcas couldn’t get to these otters and these otters survived. This makes it more likely that predation by orcas was the reason for the decline in the rest of the population.
(D) This information weakens the argument. If the orca population declined at the same time as the sea otter population, it is less likely that increased predation by the orcas caused the decline in sea otters.
(E) It is not clear how commercial fishing affects sea otters because the argument does not state that sea otters eat these fish. Moreover, the argument states that the sea otters did not suffer malnutrition so a lack of food is unlikely to be the cause of the decline in sea otters. Even if it were the case, this choice would weaken, not strengthen, the argument.
Step 1: Identify the Question
The words if true and most strengthen indicate that this is a Strengthen the Argument question.
Step 2: Deconstruct the Argument
80 to 00: Otter pop ¯
No disease, maln, so prob predators
Orcas eat seals, but seals ¯
© Orcas ate otters à pop ¯
Step 3: Pause and State the Goal
On Strengthen questions, the correct answer is a piece of information that makes the conclusion more likely to be true. What additional evidence could support the idea that the orcas were the cause of the declining otter population?
Step 4: Work from Wrong to Right
(A) An increase in the sea urchin population would be a logical result of a decline in sea otters because there were fewer otters eating the sea urchins. This information does not clarify whether orcas were the cause of the decline in otters.
(B) The argument states that the seal population declined at the same time as the sea otter population. Thus, competition for food with or predation by seals were unlikely to have been possible explanations for the decline in sea otters. Removing these as possible causes, then, does not actually strengthen the argument.
(C) CORRECT. The orcas couldn’t get to these otters and these otters survived. This makes it more likely that predation by orcas was the reason for the decline in the rest of the population.
(D) This information weakens the argument. If the orca population declined at the same time as the sea otter population, it is less likely that increased predation by the orcas caused the decline in sea otters.
(E) It is not clear how commercial fishing affects sea otters because the argument does not state that sea otters eat these fish. Moreover, the argument states that the sea otters did not suffer malnutrition so a lack of food is unlikely to be the cause of the decline in sea otters. Even if it were the case, this choice would weaken, not strengthen, the argument.
WillGetIt
This question is discussed in detail in this video: https://youtu.be/uPdDYbYpXuI?feature=shared
Responding to a pm:
Again, Official Answers are not debatable and really, I haven't seen an exception, at least in the verbal section.
Try to understand the logic of (C).
They have very smartly used the word: "surviving".
Let's take the argument first.
Premises:
Sea otter population declined - but no sign of disease and malnutrition so predators might have been responsible.
Seal population declined dramatically.
Orcas eat otters when seals are not available.
Conclusion:
Orcas must have led to otter population decline.
We need to strengthen that orcas are responsible for the huge decline in otter population.
C. Most of the surviving sea otters live in a bay that is inaccessible to orcas.
Had the option said, "Most sea otters live in a bay that is inaccessible to orcas," then the option would have weakened our argument.
But the option says, "Most of the surviving sea otters live in a bay that is inaccessible to orcas." This means that the otters that are left are the ones where orcas cannot reach. Wherever orcas can reach, otters have disappeared from there. It means that it is highly probable that orcas have been binging on otters wherever possible.
Imagine a meadow which was full of grass 2 months back. A small part of the meadow is fenced. Some cattle was introduced in the meadow two months back. What happens if after to months you see that most of the grass is gone except the small part which was fenced? The likely reason is that the cattle ate the grass and hence reduced it.
This is the same concept.
None of the other options are relevant.
A The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined.
Irrelevant
B. Seals do not eat sea otters, nor do they compete with sea otters for food.
What seals eat is none of concern. What we need to strengthen is that orcas ate up the otters.
D. The population of orcas in the Aleutian Islands has declined since the 1980s.
This doesn't strengthen that orcas ate the otters. Perhaps some orcas couldn't adapt to decrease in seal population. We don't know.
E An increase in commercial fishing near the Aleutian Islands in the 1980s caused a slight decline in the population of the fish that seals use for food.
This might affect seal population. It doesn't strengthen that orcas ate otters.
Answer (C)
Discussion on strengthen/weaken questions here: https://youtu.be/Q5SG0ZZcHKA
30 Jul 2015, 10:35
Kudos
Bookmarks
Argument to be strengthened: "orcas were immediate cause of otter population decline"
A The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined. prey increased when predator decreased - logical outcome which could have already been deducted from the passage - out
B Seals do not eat sea otters, nor do they compete with sea otters for food. relationship between seals and otters is out of scope
C Most of the surviving sea otters live in a bay that is inaccessible to orcas. those who were accessible by orcas, died because of being eaten. only those survived who could not be accessed by predators - strengthens the argument
D The population of orcas in the Aleutian Islands has declined since the 1980s. if predators number declined seals and otters should have increased - in fact weakens
E An increase in commercial fishing near the Aleutian Islands in the 1980s caused a slight decline in the population of the fish that seals use for food. we already know that number of seals declined in during that period - out of scope
Thus Correct Answer: C
A The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined. prey increased when predator decreased - logical outcome which could have already been deducted from the passage - out
B Seals do not eat sea otters, nor do they compete with sea otters for food. relationship between seals and otters is out of scope
C Most of the surviving sea otters live in a bay that is inaccessible to orcas. those who were accessible by orcas, died because of being eaten. only those survived who could not be accessed by predators - strengthens the argument
D The population of orcas in the Aleutian Islands has declined since the 1980s. if predators number declined seals and otters should have increased - in fact weakens
E An increase in commercial fishing near the Aleutian Islands in the 1980s caused a slight decline in the population of the fish that seals use for food. we already know that number of seals declined in during that period - out of scope
Thus Correct Answer: C
