A scatterplot matrix displays pairwise relationships among four measurements of the Iris dataset, colored by species using a D3 ordinal scale. The visualization arranges 4x4 grid cells, each showing a scatterplot for a variable pair, with axes rendered via d3.axisLeft and d3.axisBottom. Diagonal cells display variable name labels instead of plots. Data loads asynchronously from a CSV file, with linear scales mapping each variable's extent to plot dimensions. Rendered as SVG circles with radius 2, using d3.select and d3.csv for data binding.