A basic scatter plot displays the classic Iris flower dataset, plotting sepal length on the x-axis against sepal width on the y-axis for all 150 specimens. Each point appears as a fixed steelblue circle. The React app loads the CSV data via D3's `csv` function, then calls a separate `viz` function that uses `scaleLinear` and `extent` to compute the chart's scales. D3's `select` and a `.join` operation render the circles onto the SVG element.