This example shows an animated scatter plot of the Iris dataset with interactive dropdown menus for selecting X and Y dimensions, plus a brushing tool to highlight data points. The visualization re-renders smoothly using `d3.transition` when axes change or data is filtered. The code organizes the scatter plot as a reusable component, with menus built via a custom `d3.dispatch` event system and brushing implemented through `d3.brush`. Points are rendered as SVG circles, with highlighted selections drawn in red.