A 2021 study measured microplastic concentrations (particles per liter) in tap water from four cities: City P, 4.2; City Q, 3.9; City R, 18.7; City S, 4.5. The researchers concluded that City R is an outlier whose contamination level cannot be explained by typical urban factors. To support the "outlier" characterization, they pointed to ______
Which choice most logically completes the text using the data above?
- A
the fact that all four cities had some microplastic contamination.
- Bcheck_circle
the close cluster of Cities P, Q, and S between 3.9 and 4.5, contrasted with City R's 18.7.
- C
City S's 4.5 particles.
- D
City P's concentration of 4.2 particles.
Explanation
"Outlier" requires showing one data point sits far outside the cluster of the others. Choice B captures this directly: three cities cluster tightly (3.9-4.5) while R stands at 18.7, supporting the outlier characterization.