Industrial pollution affects water quality in urban rivers. Environmental scientists have established that nitrogen levels above 15 parts per million...
GMAT Information and Ideas : (Ideas) Questions
Industrial pollution affects water quality in urban rivers. Environmental scientists have established that nitrogen levels above 15 parts per million indicate moderate contamination, while levels above 25 parts per million represent severe contamination requiring immediate intervention. Agricultural runoff typically produces moderate contamination levels, but industrial discharge can create severe contamination. Environmental scientists monitoring the Clearwater River found contaminated sections with nitrogen readings of 32 parts per million. This finding led the scientists to conclude that ______
Which choice most logically completes the text?
the Clearwater River contamination represents the most severe case of agricultural pollution ever documented.
agricultural sources were preferred by local farmers because nitrogen compounds are more effective than heavy metals.
the contamination in the river sections required immediate intervention due to severe pollution levels.
the pollution in the river sections likely came from industrial sources because agricultural runoff was heavily regulated.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Industrial pollution affects water quality in urban rivers." |
|
| "Environmental scientists have established that nitrogen levels above 15 parts per million indicate moderate contamination, while levels above 25 parts per million represent severe contamination requiring immediate intervention." |
|
| "Agricultural runoff typically produces moderate contamination levels, but industrial discharge can create severe contamination." |
|
| "Environmental scientists monitoring the Clearwater River found contaminated sections with nitrogen readings of 32 parts per million." |
|
| "This finding led the scientists to conclude that ______" |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Scientists have contamination standards that help them determine the severity of river pollution and what actions are needed.
Argument Flow: The passage establishes contamination thresholds, explains which sources typically cause different levels, then presents a specific case (\(\mathrm{32\, ppm}\)) that exceeds the severe threshold, leading to a logical conclusion.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- The \(\mathrm{32\, ppm}\) reading is above the \(\mathrm{25\, ppm}\) threshold for severe contamination
- Severe contamination requires immediate intervention according to the standards
- The conclusion should logically connect the \(\mathrm{32\, ppm}\) finding to what this means in terms of contamination severity and required response
the Clearwater River contamination represents the most severe case of agricultural pollution ever documented.
✗ Incorrect
- Claims this is the most severe agricultural pollution case ever documented
- The passage never states this is agricultural pollution
- What trap this represents: Students might assume all river contamination comes from agricultural sources
agricultural sources were preferred by local farmers because nitrogen compounds are more effective than heavy metals.
✗ Incorrect
- Discusses farmer preferences between nitrogen compounds and heavy metals
- The passage does not mention heavy metals at all or discuss what farmers prefer
the contamination in the river sections required immediate intervention due to severe pollution levels.
✓ Correct
- States that contamination required immediate intervention due to severe pollution levels
- \(32\mathrm{ ppm}\) exceeds the \(25\mathrm{ ppm}\) threshold for severe contamination
- The passage explicitly states severe contamination requires immediate intervention
- This directly follows from the established standards
the pollution in the river sections likely came from industrial sources because agricultural runoff was heavily regulated.
✗ Incorrect
- Claims pollution likely came from industrial sources because agricultural runoff was heavily regulated
- The passage mentions nothing about regulation of agricultural sources