A lichen is made up of a photosynthetic organism and a fungus growing in symbiosis on a solid surface. Lichens absorb minerals from air and rainwater but also from the surfaces on which they grow; they cannot excrete the elements they absorb. Some varieties are very vulnerable to toxic compounds, including compounds found in polluted air. Such compounds can damage both of the symbiotic partners.

Summary
A photosynthetic organism and a fungus growing symbiotically make up a lichen. Lichens absorb minerals from the air, rainwater, and the surfaces they grow on. Lichens cannot excrete elements they absorb. Some types of lichen are very vulnerable to toxic compounds, including toxins found in polluted air. These compounds can damage the photosynthetic organism and fungus that make up a lichen.

Strongly Supported Conclusions
Serious air pollution can have adverse affects on lichen growing in the area.

A
Lichens would not be vulnerable to toxic compounds if they could excrete the elements that they absorb.
This answer is unsupported. We don’t know whether absorbing toxic compounds is the only way that these compounds could be harmful for lichens.
B
The return of lichens to a region indicates that the air quality has improved there.
This answer is unsupported. We don’t know from the stimulus whether lichens disappear in areas with poorer air quality.
C
The absence of lichens in a region indicates that the air is probably polluted in that area.
This answer is unsupported. There could be other variables besides air pollution that could affect the population of lichen. We cannot say if it is air pollution for certain.
D
The photosynthetic organism and the fungus that make up a lichen can also thrive independently of each other.
This answer is unsupported. We only know from the stimulus how these organisms function symbiotically with each other.
E
Serious air pollution in a region can cause problems for lichens.
This answer is strongly supported. If toxic compounds found in polluted air can harm either or both of the symbiotic partners, then these compounds can have adverse effects for lichens.

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Lindsey: There are, of course, many poets with cheerful dispositions; however, those I have met have much more often been disposed to melancholy. Thus, if the poets I have met are representative of poets generally, one can reasonably conclude that many poets are made melancholy by writing poetry. As everyone knows, an activity as profound and engrossing as writing poetry can be depressing.

Summarize Argument: Causal Explanation
Lindsey concludes that many poets are made melancholy by writing poetry. She concludes this because the poets she has met are more often disposed to melancholy, and because everyone knows an activity like writing poetry can be depressing.

Identify Argument Part
The claim in the last sentence is a premise used to support Lindsey’s conclusion.

A
It is a premise offered as evidence for another premise, which in turn is offered in support of the argument’s overall conclusion.
The claim independently supports Lindsey’s conclusion. It is not offered as support for another premise.
B
It is a premise for which another premise is offered as evidence.
The claim independently supports Lindsey’s conclusion. It is not supported by another premise.
C
It is the overall conclusion of the argument.
The claim is not Lindsey’s main conclusion.
D
It clarifies a claim made within the overall conclusion of the argument.
The claim does not clarify another claim. It is used as direct support for Lindsey’s conclusion.
E
It is a premise offered as direct support for the argument’s overall conclusion.
The claim is a premise and independently supports Lindsey’s conclusion.

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Researchers investigating the accuracy of eyewitness accounts staged and made a video of a crime, and showed it to test subjects. A lineup of “suspects,” none of whom was the person playing the criminal in the video, was then shown to the subjects. When the subjects were not told that the suspect might not be in the lineup, 78 percent of them misidentified one or another of the persons in the lineup as the criminal. Only 38 percent of the subjects made misidentifications when they were told that the suspect might not be in the lineup.

Summary
Researchers staged a crime and showed a video of it to test subjects. A lineup of “suspects” was then shown to the test subjects. The person playing the criminal in the video was not in this lineup. When the test subjects were not told the suspect may not be in the lineup, most of them misidentified a person in the lineup as the criminal. When the test subjects were told that the suspect may not be in the lineup, less than half of them misidentified a person in the lineup as the criminal.

Strongly Supported Conclusions
The more likely people expect to see something, the more likely people are to think they see something not actually there.

A
Eyewitnesses are no more likely to accurately select a suspect from a lineup than are people who are given an accurate verbal description of the suspect.
This answer is unsupported. There was not a test group in the stimulus where people were given a vernal description of the suspect.
B
People tend to want to satisfy the stated expectations of those who ask them for information.
This answer is unsupported. We don’t know from the stimulus whether the researchers stated to the test subjects that they expected them to identify the suspect in the lineup.
C
When specifically directed by a person of authority to say that something is among a group of things when it is not, most people will comply.
This answer is unsupported. We don’t know from the stimulus whether the researchers specifically directed the test subjects in this way.
D
People fail to recognize the physical similarities among a group of people unless they are given information in addition to visual clues.
This answer is unsupported. We don’t know from the stimulus whether the test subjects failed to recognize any similarities between people.
E
People are less likely to think they see something that is not actually present the less they expect to see it.
This answer is strongly supported. This would explain the effect of the amount of misidentifications decreasing after the information told to the test subjects by the researchers.

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