Self-study
Scientist: Support A small group of islands near Australia is inhabited by several species of iguana; Support closely related species also exist in the Americas, but nowhere else. ███ ███████ ██ ████████ ██████ ████ █████ ███ █████████████ ██ █████████ ███ ███████ ██████████████ ████ ████████ ███████████ █████ ███████ ███ ██████████ █████ █████ ██████████ ███████████ ████ ████ ██████ ██ ████████ ██████ ██████ ███ ███████ █████ ████ ███ █████████
Summarize Argument: Phenomenon-Hypothesis
The scientist hypothesizes that the iguanas’ ancestors reached the islands near Australia by rafting from the Americas. As support, he points out that the only closely related species that currently exist are located in the Americas. He also notes that the islands first formed in isolation, away from any land masses, which implies that species could only exist there now if their ancestors had somehow arrived from elsewhere.
Notable Assumptions
The scientist assumes that the closely related species in the Americas have the same ancestor as the island iguanas. He further assumes that this common ancestor has only ever lived in the Americas and nowhere else.
25.
Which one of the following, ██ █████ ████ ███████ ███ ███████████ █████████
a
A number of ██████ ███████ ████ ███████ ███ ███████ ███ ███ █████ ██ ███ █████████
The argument is only concerned with the origins of the iguana species. The potential origins of any other species are irrelevant.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
b
Genetic analysis indicates ████ ███ ██████ ███████ ██ ███ ███████ ███ █████████ ██ ███████ ████████ ████ █████ █████ ██ ███ █████████
The scientist doesn’t suggest or assume that the island iguanas are the same species as the American ones. His argument is that they merely share the same ancestor, and that this ancestor rafted from America to the islands. They may have evolved differently since that ancestor.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
c
Documented cases of ███████ ███████ ████ █████████ ███████ ████ ██████ ███ █████████
That documented cases are uncommon does not mean that this situation was impossible or even unlikely at the time.
Illusory inconsistency
Illusory inconsistency
Answer is attractive because it seems to (but doesn't actually) contradict the premises or conclusion.
d
Fossils of iguana ███████ ███████ ███████ ██ █████ ████ ███████ ███ ███████ ████ ████ █████ ██ ██████████
This suggests that the island iguanas’ ancestor may have arrived from Australia, rather than from the Americas.
Alternate explanation
Alternate explanation
Weaken: Introduce or support an alternate explanation for a phenomenon.
Strengthen: Helps to eliminate an alternate explanation for a phenomenon.
e
The lineages of ████████ █████ ███ ██████ ███████ █████ ██ █████████ ██ ██ █████ ███████ ████ ████ ██ █ ██████ █████ ██ ███ █████████████ ██ █████████
The argument is only concerned with the origins of the island’s iguana species. The potential origins of other species in other locations are irrelevant.
Failed alternate explanation
Failed alternate explanation
Weaken Qs: Answers that try to introduce an alternate explanation, but fall short, or try to explain a different phenomenon.
Strengthen Qs: Answers that try to eliminate an alternate explanation, but fall short, or try to eliminate an explanation for a different phenomenon.