This is a reusable scatter plot built with D3 v7 that visualizes 120 car records from a CSV file, showing relationships between four numeric variables (horsepower, MPG, weight, displacement) with matching dropdown controls. Users can reassign each axis, the color encoding (by cylinders, origin, or year), and the point size (by weight, horsepower, or displacement) dynamically. The point areas are scaled via `d3.scaleSqrt`, colors use `d3.scaleOrdinal` with Tableau schemes, and SVG dots update with data joins, grid lines, axes, and an interactive tooltip.