This pie chart shows the distribution of students by their test preparation course status, dividing them into "completed" and "none" groups with counts displayed on each slice. The visualization uses D3 v7 to load CSV data via `d3.csv`, aggregate counts with `d3.rollup`, generate the pie geometry through `d3.pie()` and `d3.arc()`, and render slices as SVG paths with an ordinal color scale. Labels are positioned using `arc.centroid`, and a legend is built manually with SVG rectangles and text elements alongside the chart.