This example demonstrates a simple face built from D3.js geometric primitives. It displays a yellow circle with a black stroke, two black circles for eyes, and a mouth drawn as a path using a D3 arc. The code uses the D3 `select` function to append shapes to an SVG group, which is translated to the center of the canvas. The mouth’s shape is generated with D3’s `arc` API, specifying inner and outer radii and a start and end angle in radians.