hard · SAT Reading & Writing

Environmental scientists studied the correlation between the distance from a major highway and the presence of lead in topsoil samples. They hypothesized that lead concentration would fall exponentially as distance increased, becoming negligible beyond 500 meters. The results are summarized below: Distance (m) | Lead Concentration (ppm) 10 | 450 50 | 120 100 | 35 500 | 2 Which choice most effectively uses data from the table to complete the statement? The results support the hypothesis because

1. The difference in concentration between 100 meters and 500 meters was 33 ppm.
2. Lead concentration dropped by over 300 ppm in the first 50 meters and fell to just 2 ppm at the 500-meter mark.
3. The concentration at 10 meters was 450 ppm, which is significantly above the safety threshold for soil.
4. As distance increased from 10 to 500 meters, lead levels fell consistently, proving that highway traffic is the sole cause of soil contamination.

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