A D3 line chart displays daily average air temperature in Belgium for 2021 as a single smooth curve, with a time-scaled x-axis and linear temperature y-axis. Built with React, the visualization uses `d3.scaleTime`, `d3.scaleLinear`, and `d3.line` with `curveNatural` to render an SVG path. Data comes from a local CSV file, loaded via `d3.csv`. Axes are custom React components, and the chart includes labeled axes and tick marks.