Interactive scatter plots show the relationships between pairs of measurements from the classic Iris flower dataset, with dropdown menus to select which features appear on the x- and y-axes. D3 v5 scales map sepal and petal measurements to SVG circle positions, while a categorical color scale distinguishes the three Iris species, which are also listed in a manual legend. Circles animate into place using `transition().duration()` with staggered delays. The example demonstrates reusable ES6 modules for the scatter plot, dropdown menu, and color legend components.