Between 1980 and 2000 the Sea Otter Population of the Aleutian Islands GMAT Critical Reasoning

Question: 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‘?

1. The population of sea urchins, the main food of sea otters, has increased since the sea otter population declined.
2. Seals do not eat sea otters, nor do they compete with sea otters for food.
3. Most of the surviving sea otters live in a bay that is inaccessible to orcas.
4. The population of orcas in the Aleutian Islands has declined since the 1980s.
5. 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.

‘Between 1980 and 2000 the sea otter population of the Aleutian Islands declined precipitously.’ – is a GMAT Critical question. To answer the question, a candidate can by either finding a piece of evidence that would weaken the argument or logical flaws in the argument. GMAT critical reasoning tests the logical and analytical skills of the candidates. This topic requires candidates to find the argument's strengths and weaknesses or the logical flaw in the argument. The GMAT CR section contains 10 -13 GMAT critical reasoning questions out of 36 GMAT verbal questions.

Answer: C

Explanation:

Premises:
Sea otter population declined - but no sign of disease and malnutrition so predators might have been responsible.
Sea 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.

100. 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 that orcas cannot reach. Wherever orcas can reach, otters have disappeared from there. It means that it is highly probable that orcas have been bingeing on otters wherever possible.
     ​
     Imagine a meadow that was full of grass 2 months back. A small part of the meadow is fenced. Some cattle were introduced in the meadow two months back. What happens if after two 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.

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