This interactive scatterplot lets users explore the relationships between different numeric attributes of cars from the auto-mpg dataset. Two dropdown menus, built with a reusable `dropdownMenu` function, allow selection of the variables plotted on the x and y axes. The chart itself is rendered by a custom `scatterplot` module using `d3.scaleLinear`, `d3.axisBottom`, and `d3.axisLeft` for the axes. Data updates trigger a smooth `transition` animation as circles move to their new positions over 500 milliseconds.