This bubble chart visualizes the relationship between GDP (x-axis), population (y-axis), and life expectancy (bubble size and color) for 15 countries. Data is loaded from a CSV file via `d3.csv`, and circles are positioned with `d3.scaleLinear` scales. Interactive tooltips appear on mouseover events. A legend at the right encodes life expectancy values using circle radii. The SVG rendering includes axis labels and a title, with styling applied through CSS classes.