This bar chart visualizes the average rate of hair loss across five-year age groups, using steel-blue bars on a gray SVG canvas. The chart explicitly labels the y-axis with the mean hair-loss value and the x-axis with rotated age-range labels, and a title clarifies the content. The implementation loads CSV data via `d3.csv`, bins the ages with a custom rollup using `d3.rollups` and `d3.mean`, sorts the bins, and renders the bars with `d3.scaleBand` and `d3.scaleLinear`. Axes are generated by `d3.axisBottom` and `d3.axisLeft`.