A scatter plot displays 2007 country data—GDP per capita on the x-axis, life expectancy on the y-axis, and population encoded by circle radius, colored by continent. The code uses `d3.scaleLinear`, `d3.scaleSqrt`, and `d3.scaleOrdinal` from d3.js to map the data. A `Delaunay` triangulation generates a Voronoi diagram, whose invisible cells serve as hover targets, triggering a custom tooltip that names the country and matches its fill color.