This visualization displays aggregated data about individuals under New York DOCCS custody, showing bar heights that represent the count of records for a selected variable on the x-axis against a chosen y-axis metric. Users can change both axes via dropdown menus, which re-aggregates the underlying dataset and updates the chart accordingly. The implementation uses D3 v5 functions including `d3.nest()` and `d3.rollup()` for data transformation, `d3.scaleBand()` and `d3.scaleLinear()` for scales, and `d3.axisBottom()` and `d3.axisLeft()` for axes. The visualization loads JSON data asynchronously via `d3.json()` and renders SVG rectangles with transitions on selection changes.