A radial pie chart displays the distribution of population by age group across U.S. states, using stacked arcs with a color scale for each age band. The visualization employs `d3.scaleBand` for angular positioning, `d3.scaleRadial` for radius, and `d3.arc()` to render the SVG paths. Data from `data.csv` is loaded via `d3.csv` and processed with `d3.stack`, while state labels rotate around the outer ring based on their computed angle. A legend and circular gridlines with tick marks provide reference for the radial magnitude.