This chart displays a single line for one country across one variable, with two dropdown menus to select the country and the metric (life expectancy, CPI, or tax revenue). Built with D3 v7, it renders an SVG line chart using `d3.scaleBand`, `d3.scaleLinear`, `d3.axisBottom`, `d3.axisLeft`, and a `d3.line` path generator. The dropdowns are populated from static sample data, and a change event triggers the `update` function to redraw the line and axes.