This interactive scatter plot lets users explore the relationship between pairs of numeric variables from the auto-mpg dataset. Dropdown menus, built with a reusable `dropdownMenu` component, dynamically switch which columns are mapped to the x- and y-axes. The visualization, rendered as an SVG, uses D3 v5 APIs such as `scaleLinear`, `extent`, and `axisBottom`/`axisLeft` to compute scales and axes. When a new column is selected, the circles animate to their new positions over two seconds using a staged `.transition().duration(2000).delay(...)` chain.