A smiling face is drawn with D3.js and its eyebrows animate up and down. The face is built by appending SVG shapes—a yellow circle, two eye circles, rectangular eyebrows, and an arc-based mouth—to a central group. The eyebrows move via chained `transition().duration()` calls that toggle their vertical position. The code uses D3 v5 and imports `select` and `arc` from the `d3` module, with the entire animation rendered directly in SVG.