Biologists studied four wetland sites and recorded amphibian populations along with two factors: pesticide concentration in water (high/low) and habitat fragmentation (high/low). Site A, low pesticide + low fragmentation, 320 amphibians; B, low pesticide + high fragmentation, 230; C, high pesticide + low fragmentation, 90; D, high pesticide + high fragmentation, 60. The researchers concluded that high pesticide exposure has a stronger negative effect than habitat fragmentation, and that both effects are additive rather than interactive. The data most uniquely supporting "additive rather than interactive" effects is ______
Which choice most logically completes the text using the data above?
- Acheck_circle
the consistency of the fragmentation penalty: about 90 fewer amphibians under fragmentation in low-pesticide sites (320→230) and about 30 fewer in high-pesticide sites (90→60), with the pesticide penalty similarly consistent across fragmentation levels.
- B
Site A's highest amphibian count of 320.
- C
Site D's lowest amphibian count of 60.
- D
the average count across sites.
Explanation
"Additive rather than interactive" effects require that each factor's effect is roughly the same regardless of the other factor's level. Choice B examines this directly. Note: "additive in absolute terms" or "in proportional terms" can be debated, but among the four answer choices, B is the only response that addresses additivity by examining whether each variable's effect persists similarly across levels of the other—the others speak only to single sites or averages.