This bubble chart visualizes the correlation between GDP per capita, life expectancy, and population-area ratio for 20 countries. Each circle’s position maps GDP and life expectancy, while its radius encodes population density, with color distinguishing nations. Data is loaded via `d3.csv` from `bubblechart.csv`. The visualization uses `d3.scaleLinear` for axes and size, `d3.scaleOrdinal` with `d3.schemeCategory10` for colors, and SVG circles with interactive tooltips on mouseover. A legend identifies each country.