This example visualizes the Iris dataset as a scatter plot of petal length against sepal length. It uses d3.csv to load the data and d3.scaleLinear with d3.extent to map values to screen coordinates. Circles are rendered in SVG, and d3.axisLeft and d3.axisBottom generate the scales. The plot fills the entire browser window, with data points drawn at a fixed radius of 5 pixels.