This example demonstrates a simple animated face built entirely with D3.js primitives. It shows a yellow circle head with two eyes, eyebrows, and an arc-shaped mouth, all composed of SVG shapes including circles, rectangles, and a path. A continuous two-second transition repeatedly moves the eyebrows up and down, creating a subtle animation. The code uses D3's `select` to target the SVG root, `append` to build the geometric elements, and the `arc()` generator to construct the mouth’s path, with all rendering in SVG.