The islands of Mauritius and Madagascar were once believed to have

Question

The islands of Mauritius and Madagascar were once believed to have formed simultaneously but separately, as a result of the same oceanic volcanic eruption; however, this hypothesis does not explain why Madagascar has a far lower proportion of obsidian – a rare volcanic stone that forms through the rapid cooling of lava – than Mauritius. According to the Mauritia hypothesis, these two landmasses were formed when an ancient microcontinent known as Mauritia was split apart by tectonic forces. As obsidian typically forms when streams of lava come into contact with water, on islands, it is concentrated along the coasts of the landmass. As Madagascar formed from the inland part of Mauritia, it was fairly devoid of obsidian, while the obsidian-rich coastal region became Mauritius.    1 
 1. Which of the following best describes the organization of the passage?

A. Two explanations, both found to be inadequate, are offered for a phenomenon.
B. Two hypotheses are compared and contrasted.
C. An inadequate theory is presented, and a better alternative is offered.
D. How one theory developed into another is explained.
E. A hypothesis is put forth, and evidence undermining it is discussed.

2  
 2. According to the passage, the first hypothesis described holds that

Consider each of the choices separately and select all that apply

A. an oceanic volcano erupted, forming the two islands
B. in absolute terms, the amount of obsidian found in Madagascar and Mauritius is equal
C. Madagascar and Mauritius formed at the same time

3  
 3. The Mauritia hypothesis, as described in the passage, answers all of the following questions EXCEPT:

A. Was Mauritia small relative to other continents?
B. What was the origin of the tectonic forces that split Mauritia?
C. Why does Madagascar have relatively little obsidian compared to Mauritius?
D. What happened to the inland region of Mauritia after the microcontinent split?
 E. What happened to the obsidian-rich coastal region of Mauritia after the microcontinent split?

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ribbons · Answer

Theory 1: Lava + cooling -> Problem doesnt explain obsidian -> Theory 2: Small continent split

1. C
2. A and C
3.B

Sajjad1994 · Answer

Official Explanation

1. Which of the following best describes the organization of the passage?

Mind-map

A theory about the formation of two islands is introduced  
  A limitation of this theory is highlighted   
  An alternate theory is introduced  
 How the alternate theory resolves the first theory’s limitation is explained

A.  As the mind-map indicates, although the passage highlights a shortcoming in the first theory, it does not do so for the second. Incorrect.
 
  B.  The passage does not draw a comparison between the two theories presented. Incorrect.
 
  C. Correct.    As the mind-map indicates, the passage introduces a theory about the formation of two islands and highlights a limitation of this theory; the passage then introduces an   alternative theory, for which it does not cite any shortcomings; hence, the passage can be said to present an inadequate theory and offer a better alternative.

D.  The passage does not reference a connection between the two theories it puts forward; rather, it presents them as independent hypotheses. Incorrect.

E.  Although, as the mind-map indicates, the passage begins by introducing a theory and highlighting its shortcomings, such a description does not do justice to the passage’s discussion   of the second theory, the Mauritia theory. Incorrect.

Thus, C is the correct answer choice.

Sajjad1994 · Answer

Official Explanation

2. According to the passage, the first hypothesis described holds that

Passage Map

A theory about the formation of two islands is introduced 
 A limitation of this theory is highlighted 
 An alternate theory is introduced 
 How the alternate theory resolves the first theory’s limitation is explained

A. Correct.   The passage states that  “The islands of Mauritius and Madagascar were once believed to have formed...as the result of the same volcanic eruption...” ; hence, it can be inferred that the first hypothesis described holds that an oceanic volcano erupted, forming the two islands.

B.  The passage does not reference the absolute amount of obsidian found on Mauritius and Madagascar; rather, the passage states that  “...Madagascar has a far lower proportion of obsidian...” . Incorrect.

C. Correct.   The passage states that  “...Mauritius and Madagascar were once believed to have formed simultaneously...” ; hence, it can be inferred that the first hypothesis described holds that Madagascar and Mauritius formed at the same time.

Thus, A and C are the correct answer choices.

Sajjad1994 · Answer

Official Explanation

3. The Mauritia hypothesis, as described in the passage, answers all of the following questions EXCEPT:

Mind-map

A theory about the formation of two islands is introduced 
 A limitation of this theory is highlighted 
 An alternate theory is introduced 
 How the alternate theory resolves the first theory’s limitation is explained

A.  The usage of the phrase  “...ancient microcontinent known as Mauritia...”  implies that Mauritia was small relative to other continents. Incorrect.

B. Correct.   Although the passage states that  “...Mauritia was split apart by tectonic forces...” , it does not reference the origin of these forces; hence, the origin of the tectonic forces that split Mauritia cannot be inferred.

C.  The passage states,  “As obsidian typically forms when lava flows come into contact with water, on islands, it is concentrated along the coasts of the landmass.”  and  “...Madagascar formed from the inland part of Mauritia...” ; hence, it can be inferred that Madagascar has relatively low obsidian because obsidian tends to be absent from the interior of a landmass, and Madagascar formed from the inland portion of Mauritia. Incorrect.

D.  The passage states that  “According to the Mauritia hypothesis...Madagascar formed from the inland part of Mauritia...” . Incorrect.

E.  The passage states that  “According to the Mauritia hypothesis...the obsidian-rich coastal region became Mauritius...” . Incorrect.

Thus, B is the correct answer choice.

The islands of Mauritius and Madagascar were once believed to have

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