An interactive scatter plot explores the Iris dataset, letting users choose which quantitative or categorical measurements appear on the x-axis via dropdown menus. The visualization updates smoothly with animated transitions between selections, using D3 v6's `selection.join` to handle entering, updating, and exiting circles. The chart renders as SVG, with axes from `d3.axisLeft` and `d3.axisBottom`, while the menu system is built with a reusable `d3.dispatch` pattern. New points grow from radius zero, and updates stagger with a slight delay.