A smiling face rendered in SVG uses D3's `select` and `arc` APIs to compose a yellow circle head, two black eye circles, and a mouth path formed by a donut-like arc with an inner radius of 150 and an outer radius of 170. The eyes are positioned symmetrically around the center, offset by 100 pixels horizontally and 70 pixels vertically. All elements are drawn directly via D3 selections, with the head and mouth grouped inside a translated `<g>` element, while the eyes are appended to the root SVG.