A yellow smiley face with animated eyebrows demonstrates basic D3.js DOM manipulation and SVG rendering. The code uses `d3.select`, `d3.append`, and `d3.arc` to build the face, while sequential `transition().duration()` calls move the eyebrows up and down in a two-second cycle. The static SVG elements—circle, rectangles, and path—are positioned using translation transforms, with no external data source beyond fixed constants.