Scientist: There is little doubt that the ice ages were caused by the

Question

Scientist: There is little doubt that the ice ages were caused by the unusually rich growth of vegetation worldwide. Since vegetation converts carbon dioxide into oxygen, excessive vegetation would have depleted the carbon dioxide in the atmosphere. Carbon dioxide helps the atmosphere retain the sun's heat. Thus, if this carbon dioxide is depleted, the earth cools significantly, thereby causing an ice age.

Which one of the following most accurately expresses the main conclusion of the scientist's argument?

(A) Excessive growth of vegetation worldwide could have caused one or more ice ages by depleting the carbon dioxide in the atmosphere.

(B) If the carbon dioxide in the atmosphere is depleted, the earth cools significantly, thereby causing an ice age.

(C) An excessive growth of vegetation causes the carbon dioxide in the atmosphere to be depleted.

(D) If unusually rich growth of vegetation caused the ice ages, it undoubtedly did so by depleting the carbon dioxide in the atmosphere.

(E) Unusually rich growth of vegetation worldwide was almost certainly the cause of the ice ages.

ankushsambare · Answer

The main conclusion is the statement the scientist is trying to prove.
First sentence:
“There is little doubt that the ice ages were caused by the unusually rich growth of vegetation worldwide.”
Everything after that explains why this is true.
Premises:
 
 Vegetation converts carbon dioxide into oxygen. 
 Excessive vegetation reduces carbon dioxide in the atmosphere. 
 Carbon dioxide helps retain heat. 
 Less carbon dioxide makes Earth cooler and can cause an ice age.  
So the conclusion is:
Unusually rich vegetation growth caused the ice ages.
Check choices:
(A) says “could have caused” → too weak. The author is much more certain.
(B) is only a supporting premise about carbon dioxide causing cooling.
(C) is another supporting premise about vegetation reducing carbon dioxide.
(D) talks only about the mechanism, not the main point.
(E) matches exactly:
“Unusually rich growth of vegetation worldwide was almost certainly the cause of the ice ages.”
 Answer: (E)

guddo · Answer

Scientist: There is little doubt that the ice ages were caused by the unusually rich growth of vegetation worldwide. Since vegetation converts carbon dioxide into oxygen, excessive vegetation would have depleted the carbon dioxide in the atmosphere. Carbon dioxide helps the atmosphere retain the sun's heat. Thus, if this carbon dioxide is depleted, the earth cools significantly, thereby causing an ice age.
 
 Which one of the following most accurately expresses the main conclusion of the scientist's argument?

The scientist’s main conclusion is stated at the beginning: unusually rich worldwide vegetation caused the ice ages. The rest of the argument explains the mechanism: vegetation depleted carbon dioxide, less carbon dioxide reduced heat retention, and the earth cooled.  So the conclusion is the causal claim , not one of the supporting steps in the explanation.

(A) Excessive growth of vegetation worldwide could have caused one or more ice ages by depleting the carbon dioxide in the atmosphere.

Wrong. This is too weak. The scientist is not saying this merely could have happened; the scientist says there is little doubt that it did happen.

(B) If the carbon dioxide in the atmosphere is depleted, the earth cools significantly, thereby causing an ice age.

Wrong. This is a supporting principle in the argument, not the main conclusion.

(C) An excessive growth of vegetation causes the carbon dioxide in the atmosphere to be depleted.

Wrong. This is another supporting step. It helps explain  how  vegetation could cause an ice age.

(D) If unusually rich growth of vegetation caused the ice ages, it undoubtedly did so by depleting the carbon dioxide in the atmosphere.

Wrong. This is about the mechanism, but the scientist’s main point is that vegetation actually caused the ice ages.

(E) Unusually rich growth of vegetation worldwide was almost certainly the cause of the ice ages.

Correct. This matches the first sentence and captures the main conclusion: the ice ages were caused by unusually rich growth of vegetation worldwide.

Answer: (E)

yc168 · Answer

OE for reference:

Overview:  
You are asked to select the answer choice that most accurately expresses the main conclusion of the scientist's argument. To do this, you'll need to recognize the argument's premises and how they work together to support the main conclusion. One premise is the scientist's claim that excessive vegetation would have depleted carbon dioxide in the atmosphere (because vegetation converts carbon dioxide into oxygen). Another premise is the statement that depleting the earth's carbon dioxide results in ice ages (because carbon dioxide helps the atmosphere to retain heat). Bringing these two premises together, we can infer that when there is excessive vegetation, an ice age will result.

The Correct Answer:

E  As noted in the "Overview," the scientist's premises work together to support the claim that when the earth has excessive vegetation, an ice age will result. This strongly supports the scientist's initial statement that the ice ages were caused by the unusually rich growth of vegetation worldwide. Since every other part of the scientist's argument contributes to supporting this statement, it is clearly the main conclusion of that argument. (E) is a close paraphrase of that statement, so it is the answer choice that most accurately expresses the main conclusion.

The Incorrect Answer Choices:

A  The scientist's premises do support (A)'s claim that excessive vegetation could have caused an ice age by depleting atmospheric carbon dioxide. However, the scientist makes the stronger claim that "there is little doubt" that such vegetation caused the ice ages. This goes well beyond (A)'s claim, and it also accords with the argument's premises: as noted in the "Overview," the premises establish that excessive vegetation will cause an ice age, not merely that it could have done so. Thus, (A) is too weak to represent the main conclusion of the scientist's argument.

B  The scientist does indicate that if atmospheric carbon dioxide is depleted, the earth cools significantly, thereby causing an ice age. But, as suggested by the "Overview," the scientist indicates this in order to establish a statement about the connection between excessive vegetation and ice ages. (B)'s claim functions as support for that statement, so it is a premise of the scientist's argument rather than its main conclusion.

C  The scientist does indicate that excessive vegetation growth causes atmospheric carbon dioxide to be depleted. But, as suggested by the "Overview," the scientist indicates this in order to establish a statement about the connection between excessive vegetation and ice ages. (C)'s claim functions as support for that statement, so it is a premise of the scientist's argument rather than its main conclusion.

D  The scientist's argument addresses the question of whether excessive vegetation caused the ice ages. But (D) addresses a different question: whether, assuming that excessive vegetation caused the ice ages, it did so by depleting atmospheric carbon dioxide. So (D) does not accurately express the scientist's main conclusion.

Scientist: There is little doubt that the ice ages were caused by the

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Scientist: There is little doubt that the ice ages were caused by the

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615 to 715 in 15 Days (Ria's Strategies)

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