A yellow SVG face with eyes, eyebrows, and an arc-based smile is built entirely with D3.js primitives. Circles form the eyes and face, rectangles create the eyebrows, and a path from `d3.arc()` draws the mouth. The eyebrows animate vertically through chained `transition().duration(500)`, shifting down then returning. The code reads the SVG's height and width attributes to center a root group, then positions facial features relative to that center.