This example renders a smiley face using React and D3, drawing a red circle with white outlines as the head, two smaller circles for eyes, and an arc for the mouth via the `d3.arc` API. The SVG is generated programmatically with fixed dimensions, centering the face and applying a translation transform. The code imports `React` and `ReactDOM` to mount the component, while D3 v5 provides the arc geometry with specified inner and outer radii and angle limits.