PTB.S1.Q19 - It is widely, but falsely, held that life

MCHOWDHURY-1

PrepTest B - Section 1 - Question 19

can anyone come up with an explanation for this.

Admin Note: Edited title. For LR questions, please use the format: "PT#.S#.Q# - brief description of the question."

jbantony

In this argument the author is claiming that that the notion that was widely believed that life on land could not have started only half a billion years ago as well as it starting from the ocean is false. The support has to do with these rocks that have Carbon 14 on them, which is the byproduct of life from plants and microbes absorbing and releasing it in the atmosphere. Carbon 14 is sighted as evidence because one of the ways it is found is through plants and microbes absorbing it through the atmosphere and releasing it when they die, and obviously plants and microbes indicate life. But in AC D we are presented an alternative hypothesis. It states that the Carbon 14 found was not as a byproduct of life rather it is the result from the soil that directly absorbed the Carbon 14. If Carbon 14 could be found in absence of life then it it weakens the amount of support the premise claims it has to come up with the conclusion. This is how I came to AC D.

I think there is this implicit assumption states in the stimulus, it is trying to lead us to believe that the rocks contain carbon 14 through the process of plants and microbes dying and releasing carbon 14 which is then absorbed by the rocks. But what AC D does is address that assumption, it provides with another reason for why this occurs without the need for life. Notice the term "directly" in AC D it implies that there are no intermediary steps between the soil absorbing carbon 14, it simply does so by the atmosphere.