This interactive scatter plot lets users choose which columns of the auto-mpg dataset to display on the x- and y-axes via HTML dropdown menus. The `dropdownMenu` module creates the select elements, while the `scatterPlot` module uses d3.scaleLinear, d3.axisLeft, and d3.axisBottom to render the axes. Circles transition with d3.transition over 2 seconds, animating from the center to their new positions using `transition.attr` and `transition.delay`. SVG rendering and D3 v5 selections manage updates.