A D3 scatter plot visualizes the Iris dataset by mapping petal length and sepal length onto a Cartesian grid using `d3.scaleLinear` and `d3.extent`, with circles rendered as SVG elements. The `d3.csv` loader parses numeric fields, and `d3.axisLeft` and `d3.axisBottom` generate labeled axes with custom CSS tick styling. The chart fills the browser viewport, and tooltips show point coordinates via appended `title` elements.