The dinosaurs in the late cretaceous period failed to survive on the planet because of factors such as inadequate food supplies, harsh weather, and an inability to adapt to the changing environment.

A. an inability
B. that they were unable
C. because they were unable
D. being unable
E. lacking an ability
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Official Solution:

The dinosaurs in the late cretaceous period failed to survive on the planet because of factors such as inadequate food supplies, harsh weather, and an inability to adapt to the changing environment.

A. an inability
B. that they were unable
C. because they were unable
D. being unable
E. lacking an ability

1. Correct. The sentence contains a list of factors that kept the dinosaurs from surviving on Earth: "inadequate food supplies, harsh weather, and an inability to adapt to the changing environment." In lists of examples, all the examples must be parallel (in the same form). The list has, as its elements, nouns, which are parallel. Thus, this choice contains no error. If you understand the list, this is a pretty straightforward parallelism question.
2. This choice a clause "that they were unable to communicate with Native Americans" is a part of the list instead of a noun, thus violating the parallelism.
3. As in (B) this choice is incorrect because "and because they were unable to adapt …." is a clause rather than a noun, thus violating the parallelism.
4. This choice is incorrect because "and being unable to ….." is a verb construction rather than a noun, thus violating the parallelism.
5. This choice is incorrect because "and lacking ability to …." is a verb construction rather than a noun, thus violating the parallelism.

Answer: A
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I agree with explanation. Just to remark that the explanation says
This choice a clause "that they were unable to communicate with Native Americans" is a part of the list instead of a noun, thus violating the parallelism.
Clearly from another question

I think this is a high-quality question and the explanation isn't clear enough, please elaborate. Why "an" inability and not "inabilities"?

I went for choice B
because there was a "coma"+"and" (..., and...) in choice A. The list format was: adj+noun ( inadequate food supplies, harsh weather) and underlined part seemed to distort the parallelism. Am I wrong

Hi, The sentence talks about factors because of which dinosaurs failed to survive.
Your observation is correct. All the list items are in structure as adj+Noun, but eventually it is a list of nouns. In choice B "that" modifies the entire clause "they were unable to..." and thus is not correct. In choice A it starts with noun "inability", even if it lacks adj, it still maintains list of nouns and it is correct.

The use of "and" here -
Whenever we have more than 2 elements in a list, We express them as x, y and z. "and" in this case is used in same sense and it is used to maintain the parallelism and not to distort.

Hope it helps..

I think this is a high-quality question and I agree with explanation.

AndrewN - could you please help me understand why in Option E "lacking" is not a "noun" that is acting as a gerund? The explanation says that "lacking an ability" is a verb, but I am not able to completely grasp why it is not a noun.
I often get confused in parallelism questions involving noun, gerund and '-ing' verbs.

Hello, Pankaj0901. If lacking an ability to adapt to the changing environment is an answer to the question, What is a factor that caused the demise of the dinosaurs? then the entire phrase is indeed a gerund and acts in the capacity of a noun. Note that if the same phrase were dropped into the sentence either in the beginning or after the dinosaurs, it would instead be acting as a modifier in the capacity of an adjective.

1) Lacking an ability to adapt to the changing environment, the dinosaurs in the late Cretaceous period failed to survive...
2) The dinosaurs in the late Cretaceous period, lacking an ability to adapt to the changing environment, failed to survive...

Finally, for the phrase to take on the role of a verb, we would expect to see a "helping" verb in the form of to be at the head:

3) The dinosaurs in the late Cretaceous period were lacking an ability to adapt to the changing environment and failed to survive...

I hope this information may prove useful to you down the road. Thank you for thinking to ask me.

- Andrew
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Thank you AndrewN . Very nicely answered. I should not be confused with gerund or verb at least going forward.

I think this is a high-quality question and I agree with explanation. Is it okay to have an article just before one element and not all parallel elements?

Yes, chiragthukral, a parallel list need not have an article ahead of all three items. The plural food supplies bypasses the need for an article, and neither does harsh weather require an article. But the final factor is different. It should be a noun to complete the list—supplies, weather, and inability—but a plural inabilities will not do. The sentence seems to be commenting on a general tendency that dinosaurs exhibited, a failure to adapt to changes. If the plural version will not work, and a singular version without an article will also not work—failed to survive because of inability to adapt—then we have to turn to an article or rewrite the final portion altogether.

Most importantly, the original sentence is the best answer of the five presented. (B) and (C) both launch into dependent clauses, while (D) and (E) introduce gerunds to the list for no compelling reason.

I hope that proves helpful to you. Good luck with your studies.

- Andrew
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inadequate food supplies - adj + noun
harsh weather - adj + noun
and
an inability - only noun

Can these be considered parallel, even though the third item is not of the same form?

I think this is a poor-quality question and I don't agree with the explanation. Greetings,
I have a doubt here.
After the ",and" we need an independent clause right?
Then how come Option A is the answer?

Hello, Febinroy. You may recall that a comma + and construct is also used to join elements in a list—X, Y, and Z—and that is what we see in the sentence at hand with three factors mentioned. Furthermore, there is no hard rule on the GMAT™ that a comma + and must be used to join two independent clauses. I can think of two examples from the OG in which this construct is used for a phrase at the end, most likely to avoid confusion as to whether a list was continuing.

1) Being a United States citizen...

2) Developed by Pennsylvania's Palatine Germans...

If you think some other answer in the above question is correct, especially after having checked out the two links, please let me know, and I would be happy to address your concerns.

Good luck with your studies.

- Andrew
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Hi Andrew,
Thanks for highlighting the examples. I agree with the above examples comma+and construct can be used to join elements.
But I think there is a hard rule on the GMAT that independent clauses be joined either by ",+ coordinating conjunction(FANBOYS) or by a semicolon.
Correct me if I am wrong.

Thank you

Hello again, Febinroy. I think you may be getting your parts of speech confused. Specifically, there is no independent clause within the three-element list in the original sentence. If we pick it up from factors, we can parse the elements thus:


Element 1, phrase—inadequate food supplies (adjective, adjective, noun)
Element 2, phrase—harsh weather (adjective, noun)
Element 3, phrase—an inability to adapt to the changing environment (noun, noun, adjective, noun)

The infinitive form of a verb, in this case to adapt [to], is a noun, not a verb. For example, in the sentence He wants to play, to play is a noun telling us what he wants. Likewise, adapt answers to what the dinosaurs lacked an ability.

Moreover, independent clauses can be joined by colons (:) or em dashes (—), depending on the context of the sentence: Leonardo da Vinci was a polymath: in addition to being a painter, he was also an engineer, anatomist, cartographer, and, although he lacked rigorous mathematical training, a scientist, forming theories on light diffraction, wavelengths of sound, and the behaviors of flowing liquids, theories that were hundreds of years ahead of their time.

I would urge you to relax your hard rule mindset, particularly when it comes to punctuation. And if my word is not good enough, spend some time reading through posts by GMATNinja in the dedicated Ask Me Anything About GMAT SC and Grammar thread. I know how tempting it can be to put everything into a box like there is some mathematical rule, but language and punctuation conventions behave a bit differently.

As always, good luck with your studies.

- Andrew
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