D3.js v5 builds a smiling face from SVG primitives. The code draws a yellow head circle, two eyes, rectangular eyebrows, and a mouth arc. A two-thousand-millisecond transition animation repeatedly raises and lowers the eyebrows. The example demonstrates the `d3.select` API for SVG element selection, the `d3.arc` generator for creating the mouth path, and chained `transition` calls for basic procedural animation. The face is centered using an SVG group element transformed with computed width and height values.