This example visualizes the classic Iris dataset as a scatter plot, mapping petal length to the x-axis and sepal length to the y-axis using a linear scale. It loads the CSV data via `d3.csv`, parses numeric fields, and renders circles as SVG marks with a fixed radius. The chart uses `d3.scaleLinear` for both axes, `d3.extent` to set domains, and `d3.axisLeft` and `d3.axisBottom` for tick marks, all within a full-window SVG canvas.