The rare bird, considered extinct for over fifty years and actually

Hi vjns

First, when you see "and" or "but", think about parallelism structure. Technically, we have structures
(1) contrast: A... but B....<== A and B have opposite meaning.
(2) Non-contrast: A .... and B....... <== A and B do NOT have opposite meaning.

However, we do not have any structure like: A...but B...and C.... The structure is very confusing,
A >< B and A || C
---OR---
A >< B and A >< C.
We don't know. That's why we HAVE to repeat the pronoun as in option D (repeating of "it").

The rare bird, considered extinct for over fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.

A. The rare bird, considered extinct for fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
Wrong. We need a contrast meaning here --> "and" is not correct.

B. The rare bird, which had been considered extinct for over fifty years but it was actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
Wrong. if the sentence were correct, "it" would be redundant.

C. The rare bird, which was considered extinct for over fifty years and had actually been thriving in a remote part of the Andes, made a remarkable comeback over the past decade
Wrong. "and" is wrong. In addition, "had been thriving" is bad grammar.
"made" is wrong tense --> we need present perfect tense because of "over the past decade".

D. The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.
Correct. The structure is: X was considered extinct, but X was actually thriving, and has made a remarkable comeback. ==> was thriving || has made. Both of them are opposite to "was considered extinct"

E. The rare bird was considered extinct for over fifty years, was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.
Wrong. We need "but" after "fifty years" to create a contrast meaning.

Hope it helps.

Hello, riagarg07. I am not sure why, exactly, but this question just resonated with me, and I answered it correctly in 41 seconds. Note that SC is not about racing to get the answer, but about understanding how to eliminate the answers you are sure are incorrect. In this particular instance, I was certain about one flaw or another in all four of the other answer choices. My analysis is meant to assist you and the larger community, with no disrespect to anyone who has posted before. The first thing to note with the sentence at hand is that the whole thing is underlined, so there ought to be several key differences that emerge as we compare different answers.


I took the longest considering this one. It is not a problem to place an -ed modifier in parallel with an -ing modifier, as this classic official question shows, so considered... and... thriving is not an issue in and of itself. However, I wanted and to be while instead, something to show that although the bird was considered extinct, it had, in reality, been thriving all along in a certain remote location. And simply does not convey the same meaning.


Another answer that just misses the mark. The conjunction problem has been addressed, but now we are introduced to a different problem in the subject it. Without this seemingly fitting pronoun, we would have parallel verbs to agree with the subject which, a stand-in itself for the rare bird. It can be useful to consider each clause independently with the rare bird at the head:

1) the rare bird had been considered extinct for over fifty years

BUT

2) the rare bird was actually thriving in a remote part of the Andes

This makes sense. The past perfect tense in the first clause indicates an earlier action than the one indicated by the simple past in the second clause. Here, the two clauses are bound by the conjunction and can be interchanged, with which, again, serving as the subject of each (i.e. which A but [which] B). By placing it at the head of the second clause, we rupture the parallelism and create a second independent clause, and we would expect to see a comma before but to avoid creating a run-on sentence. Consider the following sentence:

3) the rare bird had been considered extinct for over fifty years but it was actually thriving in a remote part of the Andes

These two clauses are not interchangeable. (The rare bird, it was actually thriving...) We simply cannot ignore this grammatical problem introduced by it. It breaks a parallel construct and creates a run-on sentence simultaneously. That sounds pretty awful, right?


Now it is the notion that the bird was considered extinct that adopts the simple past while its actual status adopts the past perfect, had actually been thriving. As before, the parallel elements are not in conflict. The sentence conveys that even as people believed the bird was extinct, it had, in reality, been thriving all along in this remote area of the world. The only real issue here is with the usage of the conjunction and, which should instead signal a proper contrast, as explained earlier. I have highlighted the alteration of the verb shift in the main clause from the present perfect has made in previous answer choices to the simple past made here. Although I prefer the earlier iteration to illustrate an ongoing action that has taken place over the last decade, there is no reason we absolutely cannot cap off a ten-year period by using the simple past:

The rare bird... made a remarkable comeback over the previous decade.

Once again, a single problem here proves fatal for the prospects of the answer choice.


This version of the sentence creates two independent clauses, opting for a simple past construct in each. The second independent clause contains the two parallel elements, it was actually thriving and [it] has made a remarkable comeback. The phrase over the past decade delays the second element, so the double commas surrounding it are appropriate. (A good test for double commas is to see whether the sentence is comprehensible with the self-contained phrase or clause removed, and here, you can see that the sentence would be palatable without the phrase in question.) I have highlighted the comma before the second element, as I am calling it, because it is not strictly necessary. When dealing with lengthier phrases or clauses with two elements, it is more of a stylistic choice whether to use a comma between them. I have commented on this issue recently in another post on a question that incorporates the same convention, here. In short, there are a few talking points in this answer choice, but there is nothing to argue against outright, so it is the best option so far.


There is some false parallelism going on here in the form of an apparent list. The shell of the sentence suggests that the rare bird A, B, and C—was considered... was actually thriving... and has made—but with the first two items in the list taking on a was form, we find it jarring to suddenly encounter a has in front of the third item. Removing the initial was and turning considered... into a modifier would bypass the issue altogether, but you can only go by what is on the screen. Speaking of which, I am assuming that an remarkable comeback is a typo, so I did not mark it in red. The only time I have seen an used without a vowel sound following it is when, on occasion, we get a soft consonant instead, as in, an historic moment.

There you have it. I have done the best I can to illustrate what guided my thought process as I combed through the answer choices. There is a lot to talk about in this question for sure, but I hope I have put everything together in a way that is useful to you.

Good luck with your studies.

- Andrew
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Concept tested : Proper use of Co-coordinating conjunction
but is the correct conjunction to be used here as we intent to express contrast. This leaves us with B and D. In B past perfect tense is used , however we don't intend to express any sequence in time. Notice that the non underlined part of the sentence use present perfect correctly as we want to establish a time line from the past to the present. Hence D wins. Also don't worry too much about comma placement in D as GMAT doesn't judge an answer on that basis.

I am gonna split the correct answer only:

The rare bird (subject)was considered extinct for over fifty years(first), was actually thriving in a remote part of the Andes(second), and[, over the past decade, MODIFIER] has made an remarkable comeback(third).

Hope this is what you were looking for

The bolded comma is not an isolated one but is a part of a pairas follows:

...and, over the last decade, has made a remarkable comeback.

Notice the second comma after the word decade.

Pair of commas are sometimes used to enclose the non essential modifiers in a sentence. Here we have a non essential prepositional modifier "over the last decade" enclosed inside a pair of commas.

Posted from my mobile device

The rare bird, considered extinct for over fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.

1 The rare bird, considered extinct for fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
2 The rare bird, which had been considered extinct for over fifty years but it was actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
3 The rare bird, which was considered extinct for over fifty years and had actually been thriving in a remote part of the Andes, made a remarkable comeback over the past decade
4 The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.
5 The rare bird was considered extinct for over fifty years, was actually thriving in a remote part of the Andes, and, over the past decade, has made an remarkable comeback.

A conditional clause is required, hence choices not containing but can be removed, so ACE can be removed.
between B and D, D wins due to parallelism. In B "it" is not required.
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The bird was considered extinct, but was still thriving somewhere. To show contrast, a contrasting conjunction is required; hence A and C are out.

E has a list of clauses joined by ',' and 'and'. The option does not highlight the contrast. The three clauses are not even parallel as is required because of the list structure. The bird: was considered, was thriving, has made - all three clauses need to start with 'was', but this will make the sentence nonsensical.

That leaves B and D. The conjunction 'but' requires the two clauses it joins to start with the same word.
B. The bird: which had been considered, but it was thriving. which.., but it was... - Incorrect
D. The bird: was considered extinct, it was thriving - was considered..., but it was thriving... - Correct

I think the 'it' after but, in both B and D, is unnecessary.
Experts, please correct me if I am wrong anywhere in the above explanation. Thanks!

D it is: The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.

faults in bold:
a)The rare bird, considered extinct for fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
b)The rare bird, which had been considered extinct for over fifty years but it was actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
c)The rare bird, which was considered extinct for over fifty years and had actually been thriving in a remote part of the Andes, made a remarkable comeback over the past decade
d)The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.---->correct
e)The rare bird was considered extinct for over fifty years, w ----->strange option !! it is not a complete sentence

I think option B ("The rare bird, which had been considered extinct for over fifty years but it was actually ") can be eliminated
for the following reason -
we do not have an independent clause before 'but'.
if we use 'but' we should have this structure -- independent clause, BUT independent clause.

Please correct me if I am wrong. Thanks

OreoShake, while I agree that the commas are overdone in D, it's also true that there are very few absolute rules in English grammar! Like it or not, sometimes writers--even GMAT writers!--will insert a comma that doesn't seem necessary. Remember that commas can serve to indicate a pause in speaking and are sometimes used to break up a sentence for greater clarity. Honestly, I was tempted to put a comma before "and are sometimes" in that last sentence, even though it's not the standard! (What do you think? Would it have made the sentence easier to read?) For a good example of a "stray" comma in an official question, see this post (including my comments): https://gmatclub.com/forum/covering-71- ... 06346.html
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UNSTOPPABLE12 Unlike C, B fails the test for the usage of past perfect ("had been"). To use past perfect, we need another past event (in simple past tense) that follows the event we're describing. However, B uses the present perfect ("has made"), so we can't use past perfect. It needs to be "X had been happening until/before Y happened."

However, it's easier to cut B for parallelism reasons: "which HAD BEEN but IT WAS." That's the kind of error that you cut without looking back.
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Thank you for the kind words, himanshu0123. If, in the sentence marked "1" above, we were to replace it with which, we would create nothing more than a branching relative clause within an overarching main (independent) clause.

The rare bird which had been considered extinct for over fifty years, but which was actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.

Note that either relative clause could function as a logical modifier on its own, either essential or non-essential (i.e. with double commas), although there would be no reason to keep but.

1) The rare bird which had been considered extinct for over fifty years has made a remarkable comeback over the past decade.

2) The rare bird which was actually thriving in a remote part of the Andes has made a remarkable comeback over the past decade.

You can think of the two relative clauses together as coordinate adjectives, those that modify the same noun and can be transposed without any real loss in meaning. To illustrate, notice that the following sentence is just as functional as the first, at the top of the post. I will add a comma after bird out of preference.

The rare bird, which was actually thriving in a remote part of the Andes, but which had been considered extinct for over fifty years, has made a remarkable comeback over the past decade.

We see coordinate adjectives more often as two single words (e.g., He led a long, prosperous life and He led a prosperous, long life), but they can appear as phrases or even clauses, as we see in this question.

Perhaps the issue makes more sense now. Thank you for thinking to ask, and good luck with your studies.

- Andrew
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While, I picked D cuz the meaning in (a) the better grammatical sentence was poor. I have a bit of an issue with putting a conjunction (and) changing the verb tense and having no subject before it.

Is this allowed in English? I always thought when you do parallelism you had to keep the same tense. So normally, in English when I change tense I would have put an "IT" before has made.

https://webapps.towson.edu/ows/shifts.htm


My corrected sentence would be:

The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, it has made a remarkable comeback.

This question hinges on the trick: VERB tense isn't an ISSUE.

The real hidden issues are:

* (1) essential vs non-essential modifier. (If you don't know these, Google is your friend)
* (2) parallelism within (1), preferrably showing contrast

Here it is obvious that the modifier "considered extinct for over fifty years and actually thriving in a remote part of the Andes" is ESSENTIAL as to explain the "remarkable comeback". "Extinct for over fifty years" and "actually thriving in a remote part of Andes" are contrasting points. It's preferred here to use a contrasting conjunction such as "yet", but", "however", "despite x, y" and etc..

The rare bird, considered extinct for over fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.

1 The rare bird, considered extinct for over fifty years and actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
=> Essential Modifier
No preferred contrast => Eliminate
2 The rare bird, which had been considered extinct for over fifty years but it was actually thriving in a remote part of the Andes, has made a remarkable comeback over the past decade.
=> ", which" is an Non-Essential modifier => Eliminate
Shows contrast
3 The rare bird, which was considered extinct for over fifty years and had actually been thriving in a remote part of the Andes, made a remarkable comeback over the past decade
=> ", which" is an Non-Essential modifier => Eliminate
No preferred contrast => Eliminate
4 The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback.
Modifier went into the actual sentence, by definition ESSENTIAL
Shows contrast
5 The rare bird was considered extinct for over fifty years, was actually thriving in a remote part of the Andes, and, over the past decade, has made an remarkable comeback.
Modifier went into the actual sentence, by definition ESSENTIAL
No preferred contrast => Eliminate
Bonus Mistake: "remarkable comback" is a consequence of "actually thriving" thus those cannot be stated in equal priority - parallel.

Answer:

Hi Harman95

One piece of advice on parallelism.
Go through below lecture by GMATNinja for understanding parallelism triggers, it will help a lot.
https://www.youtube.com/watch?v=bXRz0RBLNus

Now to understand option D, its better if you go by meaning approach.
"The rare bird was considered extinct for over fifty years, but it was actually thriving in a remote part of the Andes, and, over the past decade, has made a remarkable comeback."
Here subject is still the rare bird only.
Since the sentence is connected by "and", there is not need to write the subject "it" again.

I hope it helps

Whenever I am assured I have learnt something absolute in sentence correction, some gmat question creates ambiguity yet again.

As per my understanding, whenever we have a comma+conjunction form, it indicates the beginning of a new clause, meaning the noun/pronoun+verb form must exist.

In the correct answer choice, we find that after 'part of the Andes' comma+conjunction form is present, indicating that there should be clause following the conjunction. However we find no clause but rather "........., and, over the past decade, has made a remarkable comeback." Where is the subject/noun/pronoun ? For D to be correct, there must be no comma prior to 'and'.

I request an expert to help me with this predicament.

Could someone please explain why option c is wrong.

C is a great example of the emphasis the GMAT places on meaning. From a purely grammatical perspective I don't think you can say that anything is wrong with it, but when you note the contrast between "was considered extinct" and "had actually been thriving in the Andes" those two things don't go together. So joining them with "and" doesn't produce a valid, logical meaning. You wouldn't just say "I've been eating healthier and gaining weight" - those two things seem to be very incompatible...the only reason to write that sentence is to demonstrate that the input (eating healthier) is NOT leading to the predicted output (losing weight, not gaining it). The purpose of this sentence is to show that contrast between "we thought it was extinct" and "but actually it was thriving...it was just living somewhere we hadn't looked."

So phrased this way - which was considered extinct for over fifty years and had actually been thriving in a remote part of the Andes - the sentence has a meaning error. Change that "and" to a "but" and it would work. But as it's written it has a meaning problem.

Check out this official problem that tests the need for contrast the same way:

https://gmatclub.com/forum/with-only-5-percent-of-the-world-s-population-united-states-citizens-80619.html

We can eliminate E for "an remarkable comeback" as well right?

Also is the usage of Had in second option incorrect?