This example presents two side-by-side scatter plots that compare wine production and consumption quantities against a selected variable—such as happiness, GDP, or social support—across countries. A dropdown menu allows viewers to switch the y-axis variable, updating both charts simultaneously for comparison. Built with React and D3.js v6, the visualization uses `d3.select`, `d3.scaleLinear`, and `d3.axisBottom`/`d3.axisLeft` to render axes and circles with animated transitions. Hovering over a point triggers a tooltip displaying the exact quantity and selected variable value.