Geologists recently discovered marks that closely resemble worm tracks in a piece of sandstone. These marks were made...

JayDee8732 on August 7, 2017


Why is D correct?

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zgnewquist on September 12, 2019

I think the answer is because C says that "other early life forms" whereas the conclusion says that it was more likely geological processes than worms. And if it is saying "other early life forms," then it has no effect on " more likely geological processes than worms.l

zgnewquist on September 12, 2019

(In addition to the age piece previously mentioned)

Skylar on September 21, 2019

@JayDee8732 @zgnewquist Maybe I can help.

First, let's break down the argument:

Premise: Marks that resemble worm tracks were discovered in sandstone.
Premise: The marks were made much earlier than the earliest known traces of multicellular animal life (such as worms).
Conclusion: The marks are probably the traces of geological processes rather than worms.

We are looking for the answer choice that WEAKENS this conclusion.

A is incorrect because it does not add or detract anything to the argument. It states that it is "sometimes" difficult to estimate age, and the word "sometimes" is too weak to significantly alter the argument. Moreover, difficulty of process does not necessarily mean that the age estimation is incorrect.

B is incorrect because it strengthens the conclusion that the traces likely resulted from geological processes by validating the existence of such processes at the time.

C is incorrect becuase it is not directly relevant to the conclusion, since it is discussing "early life forms other than worms" whereas the argument's conclusion is only concerned with comparing the likelihood of the tracks being made by geogologcal processes to the likelihood they were made by worms. We know this becuase the conclusion uses the phrase "rather than" to narrow its claim.

D is correct becuase it weakens the argument by eliminating the possibility of the cause suggested in the conclusion. Remember, the argument suggests that the marks were either made by worms or by geological processes, and proceeds to state that geological processes are the more likely cause. Answer choice D rules out the possibility of geological processes being a viable influence, thereby leading us to conclude that the marks were likely the result of worms. This stands in direct opposition to the argument's conclusion, making it the correct answer.

E is incorrect because it does not add or detract to the argument. Even if scientists believed that worms were among the earliest forms of multicellular life to exist, this still does not mean that they existed earlier than the date that the earliest traces of multicellular life were said to exist. Moreover, this claim is weakened by the lack of evidence it discusses.

Does this make sense? Please let me know if you have any other questions!