Two dropdown menus let viewers choose which Iris flower measurements appear on the x and y axes of an SVG scatter plot. The React app loads the Iris dataset via `d3.csv` and uses `d3.scaleLinear` and `d3.extent` to set domains, while custom React components render axes and circles. As the menu selections change, the axes rescale and the scatter plot updates with the newly selected attributes, using `d3.format` for tick labels.