Self-study
In grasslands near the Namib Desert there are "fairy circles"—large, circular patches that are entirely devoid of vegetation. █████ ████ ███████ ████████ ████ █████ ██ █████ █████ ██████ ████ █████████████ ██████████ ███████████ ████ ██ ██ ███ █████████ ██████████ ██ █████ ████████ ████ █████ ███ ███████ ██ █████
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that fairy circles are created by the burrowing activities of termites. This is based on the fact that sand termite colonires are found in every fairy circle that scientists have investigated.
Notable Assumptions
The author assumes that there’s no other explanation for the formation of fairy circles. For example, maybe fairy circles are produced by animals who eat the grass in a circular fashion? Or by other kinds of animals that burrow underground?
18.
Which one of the following, ██ █████ ████ ████████ ███ ███████████ ███████████
a
Dying grass plants ██████ █████ ███████ █████ ███████ ███ ███████ ████ ██ ███ ██████
This strengthens by eliminating the possibility that fairy circles are formed by above-ground animals eating the grass. If the dying plants are damaged only at the roots, the cause is likely something underground.
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.
b
The grasses that ████ ██████ █████ ███████ ███ ████ ██ ███████ ████ ███ ████████ ███ ████ █████████ ████████ ██ ███ ███████
But why would circular patches without grass form? (B) doesn’t help establish that the cause is likely underground. It also doesn’t eliminate drought as an explanation for the circles, because drought isn’t something that would have created circles in the first place.
c
The soil in █████ ███████ █████████ ███ ██████ █████ ███████ ████ ███ ████ ██ █████ ███████████ ███████ ███ ████████
If anything, this might weaken the argument by providing an alternate explanation for the formation of fairy circles — maybe it has something to do with the higher water content of the soil.
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
Fairy circles tend ██ ████ ██ █████ ████ ███████ ████ ████████ █████ █████ ████████
This gives us information on where fairy circles tend to form. But this doesn’t suggest anything about the cause of fairy circles. Are they due to termites? Or something else?
e
Species of animals ████ ████ ██ ████ ████████ ███ █████ █████ ██████ ████ █████ ████████
We already know from the premises that sand termites are found in every fairy circle investigated. We don’t need additional support for the presence of the termites near fairy circles. The issue is whether the termites that we know are there are the cause of fairy circles.
Irrelevant corroboration
Irrelevant corroboration
Answers that provide additional support for a claim that the argument doesn't need more support for.