A scatter plot visualizes the relationship between vehicle price and mileage for 21 used cars, with each point colored by price tier: green for under $25,000, yellow for $25,000–35,000, orange for $35,000–45,000, and red for over $45,000. Built with D3.js v7, the plot uses `d3.select`, `d3.csv`, `d3.scaleLinear`, `d3.extent`, and `d3.axisBottom`/`d3.axisLeft` to render SVG axes and circles. Hovering over a point triggers a `d3.transition` that enlarges the circle and appends a temporary text tooltip showing the car’s make, model, and price.