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.
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.