A bubble chart displays average horsepower, torque, and highway MPG for car makes sourced from bubblechart.csv. Each circle’s x-position maps to horsepower, y-position to torque, and radius to MPG, with color distinguishing brands. The visualization includes axes, a circle-size legend for MPG values, and a categorical color legend. Built with D3 v7, it uses SVG, scales like `d3.scaleLinear` and `d3.scaleOrdinal`, `d3.csv` for data loading, and mouse events to show tooltips.