Self-study
Although Support some animals exhibit a mild skin reaction to urushiol, an oil produced by plants such as poison oak and poison ivy, it appears that Support only humans develop painful rashes from touching it. ██ █████ ████ ████ ████ ███ ████████ ████ ███ ██████ ███ █████ ██ █████ █████ ██████ ██████████ ████████ ████████ ███ ███ ██████ ██ █████ ██████ ██ █ ████████ ████████
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that urushiol (the chemical that causes poison ivy and poison oak reactions) did not evolve as a chemical defense for these plants. This is based on the observation that, while some animals have a mild urushiol reaction, the reaction is not severe in any animals other than humans. Furthermore, wood rats use urushiol-producing plants for nest material.
Notable Assumptions
The author also assumes that the mild skin reactions caused by urushiol don’t deter animals. The author also assumes that urushiol could not have originally evolved as a chemical defense in the plants that produce it, even if it’s no longer effective.
7.
Which one of the following, ██ █████ ████ ███ ████ ███████ ███ ███ ██████████ ██ ███ █████████
a
Wood rats build █████ █████ █████ █████ ███████ █████████ ███ ████ █████
This is irrelevant, since it does not provide any additional information about the effects of urushiol and whether it likely evolved as a chemical defense. For one thing, we don’t know if live or dead branches have different urushiol content.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
b
A number of █████████ ███████ ███ ██████ ███ ███ ██████ ███ ██ ████ ████████
This strengthens the hypothesis, since it affirms the author’s assumption that any mild reaction caused by urushiol doesn’t deter animals from using it.
Plausibility
Plausibility
Presenting evidence that corroborates (in Strengthen) or conflicts (in Weaken) with the author's hypothesized explanation or the predictions that follow from that explanation.
c
It is common ███ ██████ ██ ██████ ██████████ ██ █████████ ████████ ███████████
This is irrelevant, since the argument only makes claims about urushiol based on observations specific to urushiol; whether chemical defenses are common in other plants doesn’t matter.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
d
In approximately 85 ███████ ██ ███ █████ ███████████ ████ █████ ███████ ██ ████████ ███ █████ █ █████
This is irrelevant, since the argument has already established that urushiol is harmful to humans. We primarily care about how it affects animals.
e
Poison oak and ██████ ███ ████ ████████████ ████ ██ ██████ █████ ██████ ████ ███████ ███████ ██████ ███████████
The growth of urushiol-producing plants in human-altered ecosystems is irrelevant to the hypothesis that urushiol did not evolve as a chemical defense in those plants.