A yellow smiley face, built entirely with SVG in an HTML page, features animated eyebrows that repeatedly move up and down to change its expression. The example demonstrates fundamental D3.js v5 DOM manipulation by using `d3.select` to grab the SVG element, `d3.append` with `attr` to construct circles and rectangles for the face, and an `arc()` generator for the mouth. A recursive `transition()` chain, with a 2-second duration each way, drives the eyebrow motion within a grouped `g` element.