This pie chart visualization displays the Air Quality Index (AQI) by country, with each slice sized proportionally to the index value. The data loads from a CSV file, with the index parsed as a numeric value and countries sorted in descending order. Using d3.pie and d3.arc, the SVG renders colored slices, a legend with country names and formatted index values, and a title. A d3.scaleOrdinal with schemeCategory10 assigns colors, while the chart groups transform to center the pie.