Module
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More than 60% of journeys in Mexico City occur via
public transit, but simply reproducing a feature of
the city’s transit system—e.g., its low fares—is
unlikely to induce a significant increase in another
city’s transit ridership. As Erick Guerra et al. have
shown, transportation mode choice in urban areas of
Mexico is the product of a complex mix of factors,
including population density, the spatial distribution
of jobs, and demographic characteristics of
individuals. System features do affect ridership, of
course, but there is an irreducibly contextual
dimension of transportation mode choice.
Which choice best describes the function of the
underlined portion in the text as a whole?
A) It presents an objection to the argument of
Guerra et al. about transportation mode choice
in urban areas of Mexico.
B) It explains why it is challenging to influence
transit ridership solely by altering characteristics
of a transit system.
C) It illustrates the claim that a characteristic
associated with high transit ridership in Mexico
City is not associated with high transit ridership
elsewhere.
D) It substantiates the assertion that population
density, the spatial distribution of jobs, and
demographic characteristics are important
factors in transportation mode choice.
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10
Changes to vegetation cover and other human
activities influence carbon and nitrogen levels in soil,
though how deep these effects extend is unclear.
Hypothesizing that differences in land use lead to
differences in carbon and nitrogen levels that are not
restricted to the topsoil layer (0–30 cm deep),
Chukwuebuka Okolo and colleagues sampled soils
across multiple land-use types (e.g., grazing land,
cropland, forest) within each of several Ethiopian
locations. They found, though, that across land-use
types, carbon and nitrogen decreased to comparably
low levels beyond depths of 30 cm.
Which choice best describes the overall structure of
the text?
A) It describes a phenomenon that scientists do not
fully understand, explains a research team’s
hypothesis about that phenomenon, and then
describes a finding that led the team to refine the
hypothesis.
B) It introduces an unresolved scientific question,
presents a research team’s hypothesis pertaining
to that question, and then describes an
observation made by the team that conflicts with
that hypothesis.
C) It discusses a process that scientists are
somewhat unclear about, introduces competing
hypotheses about that process, and then explains
how a research team concluded that one of those
hypotheses is likely correct.
D) It explains a hypothesis that has been the subject
of scientific debate, discusses how a research
team tested that hypothesis, and then presents
data the team collected that validate the
hypothesis.
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CO N T I N
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