Iris Plot
An interactive scatterplot displays the classic Iris dataset, plotting sepal and petal measurements against each other. Users select the x- and y-axis variables from dropdown menus built with a custom `menu` component. The visualization renders 150 circles as SVG elements, colored by species, and animates their positions with a three-second `transition` when the axes change. D3 v5 functions `scaleLinear`, `axisBottom`, and `axisLeft` handle scaling and tick marks, while gridlines and a legend annotate the chart.