Zoologists warn of an imminent surge in the number of bird species tha

OFFICIAL EXPLANATION

The conclusion of the argument is that the rate of extinction of bird species will not surge in this century. Evidence from native North American raptors (birds of prey) is cited: namely, that even though several such species nearly vanished between 1900 and 1970, the populations of these birds have since rebounded. We are asked to select a question which would, when answered, provide information that would help us evaluate this claim.

(A) This answer choice inquires about the introduction of non-native raptors. However, the argument cites as evidence the resurgence in native raptor populations. Thus, this question does not shed light on the relevance of the evidence.

(B) CORRECT. This question points to an unwarranted assumption on the author's part. The author assumes that the rebound in native North American raptor populations since 1970 was not due to any special effort to save these species. If special efforts have been made to save these raptor species, then one might not be able to generalize this evidence to other bird species or to make predictions about population trends in the next century, using this evidence.

(C) This question is irrelevant: the argument does not depend in any way on the experience of the zoologists. It hinges instead on the trend in raptor populations that the author uses to justify his or her point.

(D) This question is irrelevant. Note that the given evidence states that "local populations of these raptors have rebounded." Thus, population increases of native North American raptors outside of North America are not pertinent.

(E) This question is irrelevant: the argument does not depend in any way on the number of acres of woodland set aside as bird refuges.
_________________

ans B..
only B gives us the reason to evaluate the argument whether these species rebound on its own or due to some special efforts of the government/ NGOs/any other org
_________________

A. How many species of non-native raptors have been introduced into North America since 1970?
We are concerned about other bird species not non-native raptors -- OUT

B. What special efforts, if any, have been made to rescue native North American raptors since 1970?
If efforts were made...then may be its because of those efforts the population of raptors increased. Are going to adopt same measures for other bird species ? --- Sound good -- Keep -- revisit

C. How many years’ experience do the zoologists have in evaluating patterns of extinction among animals?
LOL -- OUT

D. To what degree have native North American raptors migrated to other parts of the world?
I don't care! -- OUT
E. How many acres of woodland are set aside each year as bird refuges?
Ditto -- OUT

B it is

if to protect the native NA raptors, special efforts were made, then clearly the author of the argument is wrong, and the zoologists are right.
if not, then the author is right.

a correct answer to an evaluate question, if answered yes or not, either supports or shatters the conclusion.

B meets all the conditions.

A. How many species of non-native raptors have been introduced into North America since 1970?
The number of species is irrelevant in the reasoning provided

B. What special efforts, if any, have been made to rescue native North American raptors since 1970?
waht were the special effort put if any to save the bald eagle from extinction is the major factor to decide if the claim from the zoologist is correct or not.

C. How many years’ experience do the zoologists have in evaluating patterns of extinction among animals?
The experience of evalution of the patterns is irrelevant since the zoologist may study the preobserved patterns and still have vast knowledge and information rather than having first hand experience.

D. To what degree have native North American raptors migrated to other parts of the world?
The study of the north american raptor ws done throughout the world and not just in the north america therfore the degree to which they migrate is not relevant to the argument.

E. How many acres of woodland are set aside each year as bird refuges?
Out of scope.

Hello sir,

i am confused with option "D". can't we say that initially if more no. of raptor migrated and now only few were migrating due to which their population rebounded.

So answer of what no previously were migrating and what no of birds now are migrating can be helpful..

Please help and correct my reasoning.

Although, i agree with your reasoning, just want to find the flaw in my reasoning.

Hey jrk23. See if this helps you!

Firstly, migration is a seasonal thing. Birds fly to a certain place due to seasonality and then fly back. I don't think it has an effect on the population. It's like a population count, it doesn't matter what your current location is, you'd be counted based on your citizenship. Also, migratory trends usually do no change. They may change in extreme situations, but it is unlikely.

Also, you need to evaluate the options in context of the whole passage and not just the statements about the raptors. The author is saying that such population fluctuations are normal and wouldn't lead to an extinction. He says so by giving an example of a specie that almost vanished and then resurfaced. But if special efforts were made to save the population of north american raptors, we would probably need to make special efforts today or else the birds would become extinct.

IMO B is the correct answer. It is the only option that addresses any external effect of the numbers rebounding.