Self-study
In Peru, ancient disturbances in the dark surface material of a desert show up as light-colored lines that are the width of a footpath and stretch for long distances. ███ █████ ██ █████ █████████ ███ ████ ████ ████ █ ██████ █████ ███████ ████ ██████ █████ ████ ████ █ ████ █████ ████ ███████ ████████████ ███ █████ ██ ███ ██████ ██ ███████ ██████ ███ ███████████████████ ███████ ██ ████████████ ██████ ████ ████ █████ ██████ ████ ████ ████ ██████ ███████ ███████ ███ ██ ███ ████ █████ ████ ████ ███████ ██████ █████ ████ ███ █████████ ████ ███████████ ██ █ ████████ ████████ ████ ████ ████████ ██ ██ ███ ██ ███ ██████ ██ ██ ███████████ ██████ ███
Argument Breakdown
The stimulus tells us about two groups of very long, footpath-like lines found in the Peruvian desert. The first group of lines is shaped like a sunburst, with many straight lines branching out from the same point. The second group of lines is curved and forms a large bird shape. The two groups cross over each other. This phenomenon is the context we're given.
The argument we're concerned with is made by an investigator, who hypothesizes that the lines were used for aliens to land their spaceships. In support, the investigator explains that the lines wouldn't have been useful as roads: they're too closely-spaced, they end at random places, and a sunburst shape wouldn't make sense for roads.
Objective: Describe the Method of Reasoning
The investigator doesn't support the hypothesis that the lines were alien landing strips with direct evidence. Instead, the investigator eliminates another possible explanation by showing that its implications wouldn't make sense. To do so, the investigator has to assume that these are the only possible explanations, because otherwise eliminating one wouldn't show the truth of the other.
The correct answer might describe both these elements of the argument, or only one. It also might be phrased in abstract language that's hard to recognize. To avoid overlooking the correct answer, we want to tie the answer choices back to the stimulus so we can verify whether they actually describe the argument.
25.
For someone who interprets the █████ ██ █████████ ██ ████████████ ██████████ █████ ███ ██ ███ ██████████ ██ █████ ████ ███████████ ████████ ██ █████████ ████ ███ ████████ ██ ███ █████████████ ███████ ████ ███ ████ ██████ █████ ████ ███ ███ █████ ██ ████ ███████ ██████ █████████ █████████
a
In areas that ████ █████████ ██ ███████ ██████ █████ ████████ ████████ ████████████ ██ ██████ ████ ████ █████ ████ ████ ██████ █████ ████████ █████ █████████ ██ ███ ██████ █████████ ██ ██████████████ ██████████ █████
(A) tells us that native peoples from a different continent also practiced astronomy. But because we're trying to establish that these lines specifically are related to astronomy, that's not good enough. General claims about native peoples' astronomy practices don't weaken the objection about these particular lines.
b
The straight lines ███ ██████████ ████ █████ █████ ██ ██████ ██ ███ ███████ █████ ██████████ ████████████ ██████ █████ ████ ████ ████████ ██ ███████ █████████ ██████ ███ ███ ██████ █████ █████████ █ ██████████████
(B) proposes concrete relationships to astronomy for both groups of lines, effectively weakening the objection. If the sunburst directed observers to look at particular points in the sky, and the bird represented a constellation, that undermines the claim that the two groups of lines have unrelated purposes.
c
The straight-line pattern ██ ████ ██ █ █████ █████████ ███████ ██ ████████ ██ █████████████ ████ ██████████ ███████ ██████ ████ ███ ████████
There are two problems with (C). First, (C) doesn't mention the bird pattern, which means we can't undermine the objection that the patterns are unrelated. Second, (C) doesn't link the sunburst pattern to astronomy either. This again fails to weaken the objection.
d
Native Central American █████████ ████ ██ ████ ██ ███ █████ ████ ██████ █████████ ████████████ █████████ ████ ████ ████████ ██ ██████
Like (A), (D) explains the astronomical practices of certain native peoples, but there's no link to the Peruvian desert lines. This means (D) can't help us weaken the claim that the two groups of desert lines are unrelated to astronomy.
e
There is evidence ████ ███ ████ ██████ ███ ████ ████ ██████ ███ █████████████ ████████
Without more information, when the lines were made doesn't tell us about their purpose, so (E) doesn't weaken the objection. In fact, if the gap was long enough, (E) might even strengthen the objection—lines made centuries apart might be less likely to be related.