The dry mountain ranges of the western United States contain rocks

My paragraph summaries were as follows:

1.Evidence was found indicating/ providing clues to the significant radiations during O.P
(Next author might elaborate the evidence or describe further what role did the radiations play)
2.Author tells us what happens during the radiations
Marine family expanded. Radiations lasted a long while but the changes in species lasted a short while.
3. Predicting the cause of the ordovician radiation through ecological evidence
4.Concluding that the evidence is not enough to make concrete statements on the actual relationship

hi gmat ninja i have to tried to comprehend the passage as much as i can, i want you to comprehend the passage so that i can check my comprehension

Can anyone explain me why B is the correct option from Q.5?

B. They may have created conditions favorable to the evolution of many "new life-forms".

Everything looks fine except the "new life forms".As per the passage, radiations are periods when "existing" life-forms gave rise to variations that would eventually evolve into entirely "new species"

Also,in the final sentence - these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the "Ordovician radiation"

There is no mention of "new life forms" rather they explicitly mentioned "new species"

This is why i eliminated B and chose D, even though it is not completely covered in the passage.

Hey priyamvada123,

I am not sure what is your doubt regarding as the answer to question 5 as the answer is E and not B. So if you could let me know your issue, I would be glad to help you out.


Thanks.

In Question#2, can anyone explain why the correct answer is not E?

And , in fact, there is evidence of major ecological and geological changes during this period: the sea level dropped drastically and mountain ranges were formed, in this instance, rather than leading to large-scale extinctions, these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the Ordovician radiation.

Option E states that "They hastened the formation of the extensive dry regions found in the western united states.".
I must say that I was torn between option B and E, but the highlighted portion made me incline towards option E.

Experts VeritasKarishma GMATNinja ? Your thoughts, please

Also, how to tackle such questions when these two options are so so close and seem indestructible.

Hiii experts,
Can you please tell me in the 3rd question(The last sentence...) why C is wrong and E is correct because I felt like option C,D and E meant almost the same thing in one way or the other?

Hi dontmesswithme,



Option C is clearly incorrect, because even if we say that that the last sentence is a conclusion, the second part of the sentence is very vague, we cannot infer if the proposed hypothesis comes from a limited geographic area.

Option D


The author is not warning any such thing and he is also not against any such relationship. He is simply telling the reader that the information about the information about the relationship between environmental factors and the diversification of life forms is not yet understood.

whereas option E:


is the correct choice,as the author is alerting the reading in the last sentence that the relationship between environmental factors and the diversification of life forms is not yet completely understood.

Hope This Helps.
Thanks.

Hi sssanskaar,

I'll share my thoughts on the question.

I think B is a better answer than E because in E the word "extensive" is a little extreme. True that the the sea level dropped drastically, we cannot conclude that extensive dry regions found in the western United States, were formed.

B on the other hand is a lot clearer and easily inferable from the lines : "these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the Ordovician radiation."

Hope This Helps.
Thanks.

sssanskaar

The options are not close. There is a clear winner.

(B) They may have created conditions favorable to the evolution of many new life-forms.

these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the Ordovician radiation

So the passage mentions very clearly that these geologic changes may have resulted in more favourable conditions for new life forms.

(E) They hastened the formation of the extensive dry regions found in the western united states.

The geologic changes are 'sea level dropping' and 'mountains forming'. 'They' mentioned in this option are the geologic changes. How can mountain formation hasten the formation of dry regions? Mountain formation are the dry regions.
The point is that these geologic changes provided various habitats and nutrients which gave rise to many new life forms.

vaibhav003 do you have a specific question about the passage that we can answer? If your question is just about understanding the passage as a whole, check out this article for our general RC process and recommendations, or a full list of our live YouTube RC videos can be found here.

I hope that helps a bit!

Hey Guys!!
Can you please explain me why option B is Correct for Question2 and not option D, they seem very similar?

Thanks and Regards,
Rajat

Dear Experts,

In Q3, why is the answer choice (D) wrong? Is it solely based on the usage of the words 'warns' and alerts' as stated by few other explanations. Kindly help resolve.

Thanks

Hi sagarsangani123,

Please refer the below links:

https://gmatclub.com/forum/the-dry-mountain-ranges-of-the-western-united-states-contain-rocks-248026-20.html#p2528356

https://gmatclub.com/forum/the-dry-mountain-ranges-of-the-western-united-states-contain-rocks-248026-20.html#p2617630

The last sentence of the passage: "However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood."

Yes, the word: "warn" in option D is actually suggesting warning by the author. The author is not warning, he is simply informing the readers that the relationship between environmental factors and the diversification of life forms is not yet completely understood. We are simply trying to understand the tone of the sentence and infer what the author is trying to convey.

Let me know if you still have doubts.
Thanks.

Hi RajatGMAT777,




B can be inferred from the lines: "And, in fact, there is evidence of major ecological and geological changes during this period: the sea level dropped drastically and mountain ranges were formed, in this instance, rather than leading to large-scale extinctions, these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients."

These lines suggest that geological changes during the period might have resulted in evolution of many new life-forms.



Though it seems really close to option B, but the passage doesn't talk about any new species adapting to living both on both on land and in water.

Hope This Helps.
Thanks.

Can someone explain 3rd question. I am not convinced with the solution.

Can anyone explain why Option D is incorrect for question 3?

Thanks

Check out this post by VeritasKarishma, and let us know if that doesn't clear things up!