This example shows a classic smiley face rendered as an SVG using React components for each facial feature. The `BackgroundCircle`, `Eyes`, and `Mouth` components are assembled within a transformed `<g>` element centered on the canvas. The mouth is generated using the D3 `arc` API to create a path with specified inner and outer radii and angular extent. React 16.9 handles the declarative component structure, while D3 5.11 provides the geometric arc construction. The code demonstrates a clean separation of visual elements into reusable, parameterized React components.