The red-eyed cowbird breeds by parasitizing the nests of

Question

The red-eyed cowbird breeds by parasitizing the nests of orioles, among other birds. The cowbird lays its eggs in the orioles' nests while the female orioles are out searching for food. The cowbird has evolved certain traits and behaviors to ensure the success of its deception: It throws one oriole egg out of the nest for every one of its own eggs that it lays therein, and it has evolved an egg coloration similar to that of the oriole. An oriole whose nest has thus been parasitized will subsequently incubate and rear the cowbird chick, unaware of the cowbird's ploy. 
Which of the following conclusions can most properly be drawn from the information above?
 
a. The stability of oriole populations is threatened by the behavior of red-eyed cowbirds. 
 
b. The oriole does not possess any numeric ability. 
 
c. The stability of red-eyed cowbird populations depends on the proximity of nesting orioles. 
 
d. The red-eyed cowbird's behavior is not learned. 
 
e. Scientists are unable to distinguish between a red-eyed cowbird egg and an oriole egg based solely on visual examination.

vscid · Answer

Looks like an E to me as other options dont match up.

theYogi · Answer

Ok, let me give it a shot...

A: Passage does not say that the cowbird throws all the oriole eggs out to put its own eggs, so this is an assumption
B: The oriole does possess numeric ability, else the cowbird would not have evovled a trait of replacing one oriole egg for one of its own eggs
C: This is not true because the passage mentions the red-eyed cowbird breeds by parasitizing the nests of orioles,  among other birds 
D: The red-eyed cowbird's behavior is not learned, thats why it is able to deceive other birds to hatch its eggs, so this is a good conclusion
E: This may be true, but the point is that the female oriole herself is not able to distinguish her egg and the cowbird's egg. So we don't care if scientists can distinguish them or not.

I will go with   D  ....whats the OA?

mads · Answer

Ans: A.

a. The stability of oriole populations is threatened by the behavior of red-eyed cowbirds. 
 >> Yes this is the proper conclusion. As the red-eyed cowbirds throws one oriole egg out of the nest for every one of its own eggs that it lays therein. This reduces the population of oriole. 
b. The oriole does not possess any numeric ability. 
 >> Not right.  
c. The stability of red-eyed cowbird populations depends on the proximity of nesting orioles. 
 >> Passage does not specify if red-eyed cowbird lays eggs in only orioles nest that are near by. 
d. The red-eyed cowbird's behavior is not learned. 
 >> Does not seem to be a conclusion. 
e. Scientists are unable to distinguish between a red-eyed cowbird egg and an oriole egg based solely on visual examination.
 >> Not related.

xyztroy · Answer

Hi, Can you please provide the reasoning!!

vscid · Answer

xyztroy, What is the source of this q ?

theYogi · Answer

The passage says  The cowbird has evolved certain traits and behaviors to  ensure the success of its deception

This allows the cowbird to deceive other birds and make them hatch its eggs and the other birds are un-able to see the cowbirds trick and behavior, indicating that the cowbirds behavior is not learned, so   D   is the answer

Please post the OA...

hitman4683v1 · Answer

Looks like E to me too....
I think A, B and C cannot be selected. 
However I couldnt actually get the intent of option D. The confusion being: Can we interpret the statement to mean:
"The orioles cannot learn the behaviour of the cowbird"
If that is the case then actually D should be the answer.
E is, in a way, correct since somebody(probably a scientist) ascertained the evolution of the egg coloration as a premise, so we might say (might because it appears vague to me too) that the same scientist couldn't identify the egg.

vscid · Answer

Yeah thats the same reason why I chucked D out, but looks like D is the OA. I feel D is ambiguous.
The more I think of this, I think A should be the OA based on mads's reasoning. Damn!

xyztroy · Answer

Hi All,

This question is from ARCO (Peterson's) CD that contains 3 sample tests. 
OA is D.

If you guys want, I can pull up the official explanation and paste the same here.

Thanks

vscid · Answer

It wouldnt hurt !

BarneyStinson · Answer

I believe other than Powerscore, Manhattan and Kaplan, in that sequence, no other prep material is worth consideration. Princeton and Arco especially, have been pretty confusing, just like this passage here. The intent and the sentence structuring is unclear and pretty confusing and so are the answer options given too. Unnecessary debate and usually end-up in pulling out hair from already receding hair-line!!!!

xyztroy · Answer

I have read the testimony, posted in this group itself, of many GMAT test takers who scored a very high score on GMAT and recommended ARCO's tests strongly. In their opinion the difficulty level of ARCO's tests are very much at par with the actual GMAT's.

AnshulSinghai1411 · Answer

Please let me know the books for critical reasoning...i m nt a native speaker of English...and reasoning questions go above my head...i just cant undersatnd wat they want to say......can u suggest a book for CR.I want to start from basics.....

The red-eyed cowbird breeds by parasitizing the nests of

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