SAT Reading & Writing · Command of Evidence (textual)
A stream ecologist claims that the isotopic signature of marine-derived nitrogen found in forest soils near salmon-spawning streams proves…
A stream ecologist claims that the isotopic signature of marine-derived nitrogen found in forest soils near salmon-spawning streams proves that salmon are the dominant source of nutrients in these forest ecosystems. Which finding would most directly undermine this claim?
Answer and explanation
Answer: D: Some of the same forest plots also receive substantial nutrient input from other sources, such as nitrogen-fixing plants and seasonal flooding, that were not accounted for in the isotopic…
The claim requires ruling out other significant nutrient sources, and the ecologist's isotope data alone cannot do that unless competing sources are measured and excluded. D directly supplies the missing comparison: other real contributors exist and weren't accounted for, which means "dominant source" is an overclaim from this evidence. A supports the idea that marine nutrients spread through the ecosystem, which is consistent with the claim instead of being a challenge to it. C is background about salmon behavior, not nutrient dominance. B describes the method's general reliability, not this specific overclaim.
More Command of Evidence (textual) questions
- Question 1A team analyzing an iridescent glass fragment recovered from a first-century Roman burial proposed…
- Question 2A curator claims that a museum's newly acquired painting was created by a specific well-known…
- Question 26A popular claim holds that the QWERTY keyboard layout was deliberately designed to slow typists…
- Question 28A theater historian claims that a controversial ending added to a classic play during a famous…
- Question 52Cleaner wrasse fish sometimes "cheat" by biting a client fish's protective mucus instead of…
- Question 53A biographer claims that a famous novelist's reclusive later years were driven entirely by a fear…
Learn the method behind questions like this one
The SAT Reading & Writing course teaches each tested skill through lessons, step-by-step solutions to sample problems, the complete study guide and full-length practice tests.