D3 Scatter Plot
This D3 example visualizes the classic Iris dataset as a scatter plot, mapping petal length on the x-axis against sepal length on the y-axis. It uses the `d3.csv` loader to fetch and parse the remote CSV, then applies `d3.scaleLinear` to construct axes and `d3.extent` to compute their domains. The SVG chart fills the browser window, with points rendered as circles via a data join (`selectAll` and `join`). Axis labels are omitted, but `axisLeft` and `axisBottom` draw the quantitative tick marks.