AbhishekDhanraJ72 wrote:
why not E ??
Hello,
AbhishekDhanraJ72. I would be happy to offer my thoughts on (E) and the other options in an effort to help you and the community at large. Notice that the question stem is asking us to cast
the most doubt on the validity of the evidence offered in support of the naturalists' claim. That is, the evidence itself is being called into question, as opposed to the argument that that evidence is being used to support. So what evidence is on offer in the passage?
Sentence 1 provides a definition for the term
navigation in animals. There are two parts to the definition. First, the animal must be able to get to familiar territory from unfamiliar territory, and second, the destination must lie
beyond the immediate range of the animal's senses. Seems straightforward to me.
Sentence 2 gives us our claim:
polar bears can navigate over considerable distances, according to
some naturalists.
Sentence 3 is the evidence cited for the claim, namely that a polar bear
returned to its home territory after being released over 500 kilometers (300 miles) away. In other words, the distance is the evidence.
To weaken the evidence, we must find a flaw in the reasoning that a distance of 500 km traveled by a polar bear from unfamiliar to familiar territory may not necessarily fit the working definition of
navigation in animals.
Raxit85 wrote:
A. The polar bear stopped and changed course several times as it moved toward its home territory.
Not only does this information not address the evidence (at all) concerning the distance traveled, but neither does it challenge the definition we are given of the notion of
navigation in animals. Note that that definition does not specify how the animals need to navigate, whether by a straight-arrow course or one that is more circuitous.
Raxit85 wrote:
B. The site at which the polar bear was released was on the bear's annual migration route.
What a silly mistake on the part of the researchers, who got one part right but mucked up the other. Perhaps 500 km was far enough away for the polar to no longer be able to use its senses to simply get back to Point A, but if the bear used the same route once a year to return to that same destination, then it might not be unfamiliar, and that would fall outside our definition. If the evidence no longer holds to support the claim, then we have found our answer.
Raxit85 wrote:
C. The route along which the polar bear traveled consisted primarily of snow and drifting ice.
Much like the manner of travel of the bear in choice (A), the terrain over which the bear traveled is not a concern here. As long as the distance was far enough to be outside the
immediate range of the bear's senses and the animal got from an
unfamiliar Point B back to Point A, that would be good enough.
Raxit85 wrote:
D. Polar bears are only one of many species of mammal whose members have been known to find their way home from considerable distances.
Okay, great. But we do not care about other types of animals, just the polar bear in question, and if it found its way home from a considerable distance, then that could possibly
strengthen the evidence... provided, of course, that the starting point of the trek had been unfamiliar to the bear.
Raxit85 wrote:
E. Polar bears often rely on their extreme sensitivity to smell in order to scent out familiar territory.
This can appear to be an attractive option, using the rationale that if the bear had been able to smell its way back to Point A, then the 500 km distance might not have been far enough away, so the bear did not
navigate per se. However,
extreme sensitivity to smell is vague, with no range given to qualify it, and just because a bear possesses a certain extraordinary sensory ability, we cannot automatically assume that such an ability would weaken the evidence given. Perhaps the researchers had known about such capabilities of polar bears within a range of, say, 200 km, so they more than doubled that distance to provide a comfortable margin within which to observe the navigational tendencies of the animal. In short, this is a could-be-true answer, but we have to fill in some gaps and make necessary assumptions to qualify it.
I hope that helps. If you have further questions, feel free to ask.
- Andrew