This example demonstrates fundamental DOM manipulation with D3.js by building a smiley face whose eyebrows animate upward and downward. It uses D3 selections and the `arc` generator to construct the face’s circular head, eyes, rectangular eyebrows, and mouth as SVG elements. The eyebrows move via chained `transition().duration()` calls, shifting their group’s transform attribute over two seconds in each direction. The code explicitly leverages `select`, `attr`, and `append` from d3.v5, with no external data source, relying entirely on hardcoded geometric values.