A smiling face rendered as SVG demonstrates D3.js DOM manipulation and animation. Yellow circles, black-stroked elements, and an arc path form the face, eyes, and mouth. The eyebrows, appended as rectangles, move upward and return via chained `transition().duration(2000)` calls on a group. The code uses `select`, `arc`, and attribute setters to build the static geometry and animate the eyebrow group's `transform` attribute.