PrepTest 153, Section 3, Question 8
Astronomer: Conditions in our solar system have probably(51 more words not shown)
Which one of the following(28 more words not shown)
- AIt is a(20 more words not shown)
- BIt is a(32 more words not shown)
- CIt is a(23 more words not shown)
- DIt is the(18 more words not shown)
- EIt is one(16 more words not shown)
Reading the argument
What makes our solar system unusually favorable to life? My first guesses would involve things such as temperature or protection from asteroid impacts. Perhaps a system could have the right warmth for life, or be less exposed to destructive collisions. Those are possible explanations to investigate, not things this passage has established.
The astronomer points somewhere else: chemical elements heavier than hydrogen and helium. Think of an element such as iron. We are told that any conceivable life needs adequate amounts of these heavier elements and that our sun has an unusually high abundance of them for its age. So the author has identified a needed resource and a reason to think our system is unusually well supplied.
I'm still wondering about the other conditions. A place could have plenty of a needed material and be unsuitable in another way. What if its temperature were a problem? Having an advantage in one respect doesn't settle every comparison about supporting life.
What we’re looking for
But we're being asked what the life-requirement statement does, not how to repair the argument. The first sentence is the conclusion: our conditions have probably been more favorable. The requirement helps explain why the abundance of heavier elements is relevant to that conclusion. Let's look for a description of that supporting job.
Working the answers
- ACorrect
The requirement is stated without supporting evidence. We aren't given an experiment or a further reason showing why life needs those elements. The author asks us to accept it and combines it with the sun's abundance of those elements to support the favorable-conditions conclusion. Both parts of A fit: unsupported here, but used as support for something else.
- B
The first part fits—we get no evidence for the requirement. The extra step doesn't. The requirement does not establish that our sun has abundant heavy elements; that is a separate fact. The two statements work together to support the first sentence. There isn't another supported claim between the requirement and the overall conclusion.
- C
This correctly treats the statement as support, but incorrectly says evidence is offered for it. Knowing that our sun has abundant heavier elements does not prove that all life requires them. The author simply gives us that requirement.
- D
The overall conclusion is the comparison between our solar system and most others of similar age. The requirement explains why one feature of our system might matter to that comparison. It isn't the point the astronomer is trying to establish.
- E
We have two supporting statements, not two separate conclusions. One tells us what life needs; the other tells us about our sun. The argument draws a single conclusion from them about how favorable our conditions have been.
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