Q5

[ManhattanPrepLSAT1]

Question Type
Weaken

Stimulus
The argument concludes that the most reliable way to determine whether a planet has life is by determining whether the planet's atmosphere has methane. Why? Because methane completely dissappears from the atmosphere unless it is replaced by living organisms.

Anticipation
This argument rests on a connection between living organisms and the production of methane. Sure maybe some organisms do produce methane. But isn't it also possible that some do not. In the latter case, determining whether a planet's atmosphere has methane wouldn't be the most reliable way of determining whether that planet has life, because it may be that those creatures do not produce methane.

Correct Answer
Answer choice (B) jumps on the connection between the production of methane and living beings and undermines it.

Incorrect Answers
(A) is too weak. This answer leaves open the possibility that these other ways of detecting life are not the most reliable way.

(C) is out of scope. While we may not be able to detect methane yet in other planets' atmospheres, it may be the most reliable way to determine whether that planet has life. The argument does not rest on our own current capabilities.

(D) is too weak. The small amounts of methane may nonetheless be more than enough to detect.

(E) is out of scope. Just because we haven't found methane in the atmosphere's of other planets doesn't mean that searching for methane is not the most reliable way of determining whether a planet has life.


#officialexplanation

[lolitatrekkie]

Why is answer choice B correct and not A?

Is A wrong because since the stimulus says that detecting whether or not a planet has methane is the most reliable way to detect the presence of life on a planet, the line of reasoning from stimulus isn't saying that it's "the only way" to detect life on a planet so answer choice A wouldn't help weaken it?

Since answer choice B states that not all living beings have the ability to biologically produce methane I was struggling to see how it weakens the argument. All we know is that when biological life forms are replenished from the methane, it doesn't completely disappear from the planet's atmosphere through various chemical reactions. I'm guessing that if there is no methane in the planet's atmosphere then it proves that there are no biological life forms and answer choice B would prove otherwise.

Is my line of reasoning correct?

Thanks!

[AshleyT786]

But I thought some statements (not all) were too weak to have an impact on arguments in strengthening and weakening questions.