A smiling face built from D3.js SVG shapes animates its eyebrows upward and back down. The code uses `d3.select` to append circles, rects, and an `arc()`-generated path onto a 960×500 SVG, with a yellow circular head, black-outlined eyes, and a curved mouth. Eyebrow motion is driven by chained `transition().duration(2000)` calls that translate the eyebrow group, demonstrating sequential SVG attribute tweening.