This example uses D3.js to construct a simple animated face from SVG shapes. It shows a yellow circle as the head, two eyes, and eyebrows that move up and down via chained `.transition()` calls over two seconds each, plus a mouth drawn as an arc. The code relies on D3's selection API (`d3.select`) and the `d3.arc` generator to define the mouth's path, with all elements grouped and translated to center the face.