This pie chart visualizes supermarket sales data, showing each city’s total rating as a proportional slice of the whole. The D3 v5 code uses `pie()` to compute angles, `arc()` to generate SVG path segments, and `scaleOrdinal` for slice colors. A legend maps each city to its rating value, formatted with `format('.4~g')`. Data is loaded asynchronously from a CSV file using `d3.csv`.