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555-605 Level|   Science|   Short Passage|                  
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The dry mountain ranges of the western United States contain rocks 28 Mar 2021, 01:58
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Q3 - option D is wrong not because author warns and uses strong tone
but because author is not trying to tell the readers to see a connection between 'biological' & 'geologic' changes.
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The dry mountain ranges of the western United States contain rocks 02 Apr 2021, 14:00
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The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life. This rock record provides clues about one of the most significant radiations (periods when existing life-forms gave rise to variations that would eventually evolve into entirely new species) in the history of marine invertebrates. During this radiation the number of marine biological families increased greatly, and these families included species that would dominate the marine ecosystems of the area for the next 215 million years. Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation. 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. However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood


1. The passage is primarily concerned with

(A) evaluating the evidence of a major geologic period and determining its duration
(B) describing an evolutionary phenomenon and speculating about its cause
(C) explaining the mechanisms through which marine life-forms evolved during a particular period
(D) analyzing the impact on later life-forms of an important evolutionary development
(E) contrasting a period of evolutionary change with other such periods

Show more
From the answer option B, it seems that there is no opinion of the author in the passage! But, the last line in the passage indicates that this highlighted part is the opinion of the author. Am I missing anything, experts?
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The dry mountain ranges of the western United States contain rocks 14 May 2021, 21:38
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TheUltimateWinner
Quote:
The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life. This rock record provides clues about one of the most significant radiations (periods when existing life-forms gave rise to variations that would eventually evolve into entirely new species) in the history of marine invertebrates. During this radiation the number of marine biological families increased greatly, and these families included species that would dominate the marine ecosystems of the area for the next 215 million years. Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation. 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. However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood


1. The passage is primarily concerned with

(A) evaluating the evidence of a major geologic period and determining its duration
(B) describing an evolutionary phenomenon and speculating about its cause
(C) explaining the mechanisms through which marine life-forms evolved during a particular period
(D) analyzing the impact on later life-forms of an important evolutionary development
(E) contrasting a period of evolutionary change with other such periods

From the answer option B, it seems that there is no opinion of the author in the passage! But, the last line in the passage indicates that this highlighted part is the opinion of the author. Am I missing anything, experts?
Show more

TheUltimateWinner I'm no expert but see if this helps -

1. You can't conclude that the last line is the author's view, per se. It might very well be a part of the description. If a phenomenon is not conclusive, the author will include this point in his/her description of that phenomenon.
2. Coming to the answer choice - Usage of the words describing and speculating does not imply that the author cannot include his/her opinion in 1 sentence. I don't think the GMAT or english, in general, is so rigid.
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The dry mountain ranges of the western United States contain rocks 07 Jun 2021, 22:50
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The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life
I am confused in " dating back 440 to 510 million years , to the Ordovician period ".
Please explain me how this part is functioning grammatically.
Thank you
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The dry mountain ranges of the western United States contain rocks 08 Jun 2021, 23:37
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"The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life."

Basic structure of the sentence - The ranges contain rocks

Modifiers for "rocks" -
- dating back 440 to 510 million years, to the Ordovician period,
- and teeming with evidence of tropical marine life

The rocks date back millions of years (440 million to 510 million). That was the Ordovician period. (the various periods of Earth's history are discussed here: https://en.wikipedia.org/wiki/Geologica ... y_of_Earth
Check out the Ordovician period)

The rocks are teeming with evidence of tropical marine life.
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The dry mountain ranges of the western United States contain rocks 09 Jun 2021, 00:05
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VeritasKarishma
Thank you ma'am.
Still,I am confused how you linked date back million of years (440 to 510) to Ordovician period.
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The dry mountain ranges of the western United States contain rocks 09 Jun 2021, 01:00
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Abhivas
VeritasKarishma
Thank you ma'am.
Still,I am confused how you linked date back million of years (440 to 510) to Ordovician period.
Show more

... rocks dating back millions of years, to the Ordovician period, and teeming with ...

"to the Ordovician period" is a non essential prepositional phrase modifying "dating back", the present participle modifying "rocks"

We routinely use either of the two:

dates back millions of years
or
dates back to the Ordovician period

Here, both are combined with "to the Ordovician period" acting as a non essential prepositional phrase.
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The dry mountain ranges of the western United States contain rocks 14 Jun 2021, 16:19
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EXPERTS, Please correct me if my analysis is wrong. I am trying to contribute to the community and at the same time trying to learn my mistakes from others. As explanations in RC section is not organized. this is an effort so that others can find all the explanation in one place.

Question 1:
A- Irrelevant. No evaluation, no determination of period. OUT
B- It describes an evolutionary phenomenon. And, well, it also speculates the cause. Let's keep this
C- some possible causes and results are there but no mechanism is menitoned in the passage. OUT
D- There was no discussion on "impact on later life-forms". OUT
E- No contrasts are in the passage. OUT
Only B remains. that is the Answer.

Question 2:
The only indication about "Ordovician period" we get in the passsage is "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."
Means not extinctions, but "enriched pattern of habitats and nutrients"

A- No comparisons. No indication like that. OUT
B- Seems logical. As there was "enriched pattern of habitats and nutrients", this might help for new life forms. Keep it.
C- Seems trap. As sea levels dropped so marine species of shallow water died ? This happened before the " Ordovician period", not during. But it is opposite. OUT
D- "both on land and in water" ?? Out of scope. OUT
E- Passaged does not clearly indicate that dry region was created during Ordovician period. OUT
Only B remains. B correct.

Question 3:

A- No, it does not say that. OUT
B- "importance of the Ordovician radiation". Out of scope. OUT
C- Out of scope. It does not say that evidence is insufficient. It says the relationship is not fully understood.OUT
D- It does not warn "Agianst seeing connection" rather warns the connection is not fully understood. OUT
E- This says "current knowledge cannot completely explain the relationship". Exactly. CORRECT.
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The dry mountain ranges of the western United States contain rocks 25 Oct 2021, 03:22
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Q2:

2. Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period?

(A) They were more drastic than those associated with other radiations.
(B) They may have created conditions favorable to the evolution of many new life-forms.
(C) They may have caused the extinction of many of the marine species living in shallow waters.
(D) They may have been a factor in the development of new species adapted to living both on land and in water.
(E) They hastened the formation of the extensive dry regions found in the western united states.


Can anyone please help why (D) is wrong and (B) correct? based on which lines are the inferences being made?
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The dry mountain ranges of the western United States contain rocks 28 Oct 2021, 08:37
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makshay62
Q2:

2. Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period?

(A) They were more drastic than those associated with other radiations.
(B) They may have created conditions favorable to the evolution of many new life-forms.
(C) They may have caused the extinction of many of the marine species living in shallow waters.
(D) They may have been a factor in the development of new species adapted to living both on land and in water.
(E) They hastened the formation of the extensive dry regions found in the western united states.


Can anyone please help why (D) is wrong and (B) correct? based on which lines are the inferences being made?
Show more



Hi makshay62,

Please refer the below reply by expert here:

https://gmatclub.com/forum/the-dry-mountain-ranges-of-the-western-united-states-contain-rocks-248026-20.html#p2618624

I am not an expert, but do let me know if my below post helps.

https://gmatclub.com/forum/the-dry-mountain-ranges-of-the-western-united-states-contain-rocks-248026-20.html#p2646326


Thanks.
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The dry mountain ranges of the western United States contain rocks 28 Oct 2021, 16:40
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Question 2


makshay62
Q2:

2. Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period?

(A) They were more drastic than those associated with other radiations.
(B) They may have created conditions favorable to the evolution of many new life-forms.
(C) They may have caused the extinction of many of the marine species living in shallow waters.
(D) They may have been a factor in the development of new species adapted to living both on land and in water.
(E) They hastened the formation of the extensive dry regions found in the western united states.


Can anyone please help why (D) is wrong and (B) correct? based on which lines are the inferences being made?
Show more
The passage tells us that "geological changes" during the Ordovician period "resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the Ordovician radiation."

Earlier in the passage, we learn that radiations are periods when "existing life-forms gave rise to variations that would eventually evolve into entirely new species." So, the geological changes during the Ordovician period led to enriched habitats, which in turn allowed entirely new species to evolve.

Let's start with answer choice (D):

Quote:
(D) They may have been a factor in the development of new species adapted to living both on land and in water.
Show more
The passage supports the idea that the geological changes lead to the development of new species. However, it doesn't specify what these changes entailed. As a result, it doesn't support the idea that the new species were "adapted to living on both land and water." For all we know, the new species could have lived entirely in water, or entirely on land.

Since we just don't know, (D) is out.

Let's consider (B):

Quote:
(B) They may have created conditions favorable to the evolution of many new life-forms.
Show more
As discussed above, this statement is fully supported by the passage, so (B) is correct.

I hope that helps!
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The dry mountain ranges of the western United States contain rocks 06 Jan 2022, 23:47
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However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood.


The function of this sentence:

(D) it warns the reader against seeing a connection between the biological and geologic changes described in the passage.

The sentence does not warn against a connection. It warns that the connection isn't completely understood. The sentence does not say that there isn't a connection; it says that the connection isn't understood completely.

(E) it alerts the reader that current knowledge cannot completely explain the relationship suggested by the evidence presented in the passage.

Correct. It alerts that though the passage suggests evidence of the relation, the actual relation is not completely understood using the evidence.

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The dry mountain ranges of the western United States contain rocks 13 Mar 2022, 10:32
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Can someone help me to understand the question 1's answer? In the passage, author mentioned about evidence by mentioning, "And , in fact, there is evidence of major ecological and geological changes during this period". The answer (B) is describing an evolutionary phenomenon and speculating about its cause and it has speculation which is the complete opposite of evidence. What am I missing here?
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The dry mountain ranges of the western United States contain rocks 28 Mar 2022, 11:44
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Question 1


jarbit
Can someone help me to understand the question 1's answer? In the passage, author mentioned about evidence by mentioning, "And , in fact, there is evidence of major ecological and geological changes during this period". The answer (B) is describing an evolutionary phenomenon and speculating about its cause and it has speculation which is the complete opposite of evidence. What am I missing here?
Show more
You're right that the author introduces some evidence in the passage, but to answer this question we're looking for the author's primary purpose. In other words, why did the author write this passage?

To answer these questions, first break down the structure of the passage as a whole. Here's an example of such a breakdown:

  • First, the author discusses some rocks that provide clues about a "radiation" of life-forms.
  • Then, the author suggests that "external factors" caused this radiation, and provides some evidence for this suggestion.
  • Finally, the author admits that the "actual relationship between these environmental factors and the diversification of life forms is not yet fully understood."

So, why did the author write this passage? From the above, we can tell that he/she wanted to discuss the reasons behind the radiation of life-forms. While the author does have one suggestion to explain the radiation, he/she also states that this issue is not yet fully understood.

This analysis fits nicely with option (B):
Quote:
(B) describing an evolutionary phenomenon and speculating about its cause
Show more
The author describes the radiation of life-forms and speculates that environmental factors might have caused it.

(B) is the correct answer to question 1.

I hope that helps!
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The dry mountain ranges of the western United States contain rocks 25 Jul 2022, 22:56
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Question 1


jarbit
Can someone help me to understand the question 1's answer? In the passage, author mentioned about evidence by mentioning, "And , in fact, there is evidence of major ecological and geological changes during this period". The answer (B) is describing an evolutionary phenomenon and speculating about its cause and it has speculation which is the complete opposite of evidence. What am I missing here?
You're right that the author introduces some evidence in the passage, but to answer this question we're looking for the author's primary purpose. In other words, why did the author write this passage?

To answer these questions, first break down the structure of the passage as a whole. Here's an example of such a breakdown:

  • First, the author discusses some rocks that provide clues about a "radiation" of life-forms.
  • Then, the author suggests that "external factors" caused this radiation, and provides some evidence for this suggestion.
  • Finally, the author admits that the "actual relationship between these environmental factors and the diversification of life forms is not yet fully understood."

So, why did the author write this passage? From the above, we can tell that he/she wanted to discuss the reasons behind the radiation of life-forms. While the author does have one suggestion to explain the radiation, he/she also states that this issue is not yet fully understood.

This analysis fits nicely with option (B):
Quote:
(B) describing an evolutionary phenomenon and speculating about its cause
The author describes the radiation of life-forms and speculates that environmental factors might have caused it.

(B) is the correct answer to question 1.

I hope that helps!
Show more

Hi,

Please can you help explain what is wrong with option C, "explaining the mechanisms through which marine life-forms evolved during a particular period".

Will "the mechanisms through which marine life-forms evolved" be different from "the causes causing the phenomenon"? Wont causes be a part of the mechanism through which marine life-forms evolved?

Thanks
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The dry mountain ranges of the western United States contain rocks 26 Jul 2022, 22:35
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Dear KittyDoodles,
passage does not describe any mechanisms through which marine life-forms evolved.
The passage says about radiation, changes, and potential cause.

- During this radiation the number of marine biological families increased greatly
- Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation
- However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood


The answer C does not capture the sense of the passage. Ask yourself, why the author has written the passage?
to explain the mechanisms through which marine life-forms evolved during a particular period ?

Hope it helps
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The dry mountain ranges of the western United States contain rocks 25 Aug 2022, 08:02
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Question 1


KittyDoodles
GMATNinja

jarbit
Can someone help me to understand the question 1's answer? In the passage, author mentioned about evidence by mentioning, "And , in fact, there is evidence of major ecological and geological changes during this period". The answer (B) is describing an evolutionary phenomenon and speculating about its cause and it has speculation which is the complete opposite of evidence. What am I missing here?
You're right that the author introduces some evidence in the passage, but to answer this question we're looking for the author's primary purpose. In other words, why did the author write this passage?

To answer these questions, first break down the structure of the passage as a whole. Here's an example of such a breakdown:

  • First, the author discusses some rocks that provide clues about a "radiation" of life-forms.
  • Then, the author suggests that "external factors" caused this radiation, and provides some evidence for this suggestion.
  • Finally, the author admits that the "actual relationship between these environmental factors and the diversification of life forms is not yet fully understood."

So, why did the author write this passage? From the above, we can tell that he/she wanted to discuss the reasons behind the radiation of life-forms. While the author does have one suggestion to explain the radiation, he/she also states that this issue is not yet fully understood.

This analysis fits nicely with option (B):
Quote:
(B) describing an evolutionary phenomenon and speculating about its cause
The author describes the radiation of life-forms and speculates that environmental factors might have caused it.

(B) is the correct answer to question 1.

I hope that helps!

Hi,

Please can you help explain what is wrong with option C, "explaining the mechanisms through which marine life-forms evolved during a particular period".

Will "the mechanisms through which marine life-forms evolved" be different from "the causes causing the phenomenon"? Wont causes be a part of the mechanism through which marine life-forms evolved?

Thanks
Show more
The main issue with (C) for question 1 is the word "explaining." The author doesn't actually know what caused the radiation -- he/she just presents some potential factors. So, we can't say that the passage is primarily concerned with "explaining" the mechanisms through which marine life-forms evolved during a particular period.

(B) is a much better fit: the author describes the radiation, and then speculates about its cause.

I hope that helps!
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The dry mountain ranges of the western United States contain rocks 03 Oct 2023, 07:13
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I took 18:37 mins in total. I was taking down the points such that what does each statement mean as well as author's opinion. Alas! I got a perfect 0 :) {To be honest, I at least expected 2/3 to be correct... }

The answers what I have chosen :
Q1: C
Reason , The question states about what does the passage mainly deals with. Since it talks about the Western US's rocks which dates back 440-510 M years ago to Ordovician Period, which suggests that there's evidence of marine life formation and further the passage talks about it. I opted option C. But, the official answer seems to be Option B, which states that the passages majorly talks about evolutionary phenomenon and speculating the case.

Please help me with this case.

Q2: A
Question : "Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period? "

Reason why I have opted for option A is , {Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation.}
Which led to Ordovician period , right?

Although option B too sounds favourable, But that's also a reason which helped in formation of Ordovician period, right?
As the lines of passage states {ather 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.}

Isn't the question stressed on what happened during the Ordovician period but not what led to the Ordovician period??

Q3: D

The last sentence states the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood which means to say to the readers to be cautioned about the connection between biological (diversification of life forms) and geologic changes (environmental factors) , right?

Why is option E was correct?!

Skywalker18 , GMATNinja , bb , abhimahna , poojaarora1818 can anyone help me out?

Thank You.
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The dry mountain ranges of the western United States contain rocks 13 Jan 2024, 08:56
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Questions 1, 2, & 3


Nikkz99
Q1: C
Reason , The question states about what does the passage mainly deals with. Since it talks about the Western US's rocks which dates back 440-510 M years ago to Ordovician Period, which suggests that there's evidence of marine life formation and further the passage talks about it. I opted option C. But, the official answer seems to be Option B, which states that the passages majorly talks about evolutionary phenomenon and speculating the case.

Please help me with this case.
Show more
Take another look at (B):

Quote:
(B) describing an evolutionary phenomenon and speculating about its cause
Show more
This one seems pretty air-tight. The passage describes the evolutionary phenomenon, "radiation." And phrases such as, "suggesting that external events were major factors in the radiation," speculate about the cause.

Now go back to (C):

Quote:
(C) explaining the mechanisms through which marine life-forms evolved during a particular period
Show more
Well, the last sentence of the passage is: "the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood." A relationship that isn't understood can't really be an explanation right?

In other words, the author is speculating about causes he doesn't understand, not explaining them. (C) is a classic "almost-but-not-quite" trap, and (B) is spot-on, so (B) wins for Q1.

Q2


Nikkz99
Q2: A
Question : "Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period? "

Reason why I have opted for option A is , {Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation.}
Which led to Ordovician period , right?

Although option B too sounds favourable, But that's also a reason which helped in formation of Ordovician period, right?
As the lines of passage states {ather 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.}

Isn't the question stressed on what happened during the Ordovician period but not what led to the Ordovician period??
Show more
The problem with (A) is that we know nothing about other radiations, so there's no way to know if the Ordovician radiation is more drastic. Maybe they were all like this. (Or maybe they were even more extreme!)

And for (B) it sounds like you're confusing the Ordovician period, a time frame during which many geological changes occurred, and the Ordovician radiation, which is the evolutionary phenomenon that took place during the Ordovician period.

Put another way, the changes during the period led to the radiation. This is precisely what (B) is saying.

Q3


Nikkz99
Q3: D

The last sentence states the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood which means to say to the readers to be cautioned about the connection between biological (diversification of life forms) and geologic changes (environmental factors) , right?

Why is option E was correct?!
Show more
Take a look at that last sentence again:

Quote:
However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood.
Show more
So we know there's some relationship between the environmental factors mentioned in the passage and evolution of all kinds of fun, new species, but we don't fully understand it.

That's basically what (E) says. If we don't full understand the relationship, seems fair to say that current knowledge cannot completely explain the relationship, right? So (E) is our answer. No need to overcomplicate it.

I hope that helps!
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The dry mountain ranges of the western United States contain rocks 30 Sep 2025, 07:45
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