This example uses D3.js v5 to create a smiling face whose eyebrows animate upward and downward in a repeating loop. The SVG face is composed of a yellow circle for the head, two eyes, and an arc-shaped mouth created with D3’s `arc()` geometry generator. The animation relies on D3’s `transition()` method, which automatically tween the `transform` attribute of the eyebrow group over a 2000-millisecond duration. The code demonstrates fundamental DOM manipulation by selecting the root `svg` element and appending grouped shapes.