A bubble chart displays patient age and sodium-to-potassium ratio, with bubble size encoding the count of patients per drug and color distinguishing drug types. The visualization uses D3 v6 to load CSV data from a GitHub repository, render SVG circles, and apply scales via `d3.scaleLinear`, `d3.scaleSqrt`, and `d3.scaleOrdinal`. Axes, labels, and a legend are added using `d3.axisLeft` and `d3.axisBottom`, with data aggregated through `d3.rollup`.