This visualization builds a smiley face from primitive SVG shapes using React and D3. It draws a yellow circle with a black border as the face, two small circles for eyes, and a path for the mouth generated with the `d3.arc` API. The code defines reusable React components, such as `BackgroundCircle`, and positions elements relative to a centered transform. The mouth is rendered as an arc with inner and outer radii, spanning a half-circle angle range, demonstrating how to compose geometric forms programmatically.