This example displays a pie chart of student grade data, showing each grade category as an arc with a proportional segment, and includes labels for the values and a legend identifying countries. The chart uses D3.js to fetch the CSV data, compute the pie layout using the `pie` function, and render the arcs and text with `arc` and `scaleOrdinal` for colors. The code also organizes the visualization with SVG `g` elements and uses a color array to differentiate the sections.