This example displays a donut-style pie chart of US state pollution data, drawn with SVG and D3 v5. The visualization uses `d3.pie` to compute arc segments and `d3.arc` for centroid labels, with a categorical color scale from `d3.scaleOrdinal`. Population values, fetched from a CSV, are shown inside each slice, while a legend lists states and their corresponding millions. The code also leverages D3’s `select` and `format` APIs for layout and number formatting.