A yellow smiley face rendered as a React SVG component, with a circular background, two black eyes, and a curved mouth. The face is centered in a 960 by 500 viewport, built from three reusable components: `BackgroundCircle`, `Eyes`, and `Mouth`. The mouth shape is generated using `d3.arc` from D3 v6, while the rest of the geometry uses plain SVG circles and paths. The example demonstrates composing D3 shape generators with React JSX for declarative data visualization.