Diagnostic Test 9 Practice Test

An economist contends that a downtown congestion charge can reduce average commute times across an entire metropolitan area, not just inside the toll zone. The claim is that by discouraging peak-hour car trips into the core, the policy alters route choices and departure times region-wide, easing bottlenecks on feeder highways and suburban arterials. Critics say any observed improvements are confined to the tolled district or coincide with unrelated factors such as seasonal slowdowns or fuel price spikes. The economist maintains that if the policy works as claimed, mean peak travel times should fall in suburbs as well, relative to similar metros without a charge, even after accounting for seasonal patterns.

Which finding, if true, would most directly support the scholar's claim?

Urban ecologists debate why some nocturnal insect populations decline in brightly lit cities. A biologist advances a specific mechanism: artificial night light shifts the timing of courtship and mating, so adults miss optimal windows, reducing reproductive success. If this is right, experiments that manipulate light and then measure both mating timing and fecundity should detect delays and fewer viable offspring. Findings about diurnal species, or citywide population trends without mechanism, would be less informative. The most persuasive evidence would show light exposure itself causing altered timing and lower reproduction. Because many nocturnal insects cue behaviors to darkness length and spectral composition, controlled comparisons between lit and dark conditions can isolate the effect of light. Correlational surveys alone cannot adjudicate whether light causes the decline.

Which finding, if true, would most directly support the biologist's claim?