A stacked bar chart visualizes the distribution of three iris species (setosa, versicolor, virginica) across sepal length values. The chart uses d3.csv to load the Iris dataset and d3.stack to create the stacked series, with d3.scaleOrdinal for color mapping. Each bar segment’s height represents the sepal width contribution per species, rendered as SVG rectangles via D3’s data joins and axis scales (d3.scaleBand, d3.scaleLinear). A legend identifies species colors.