Four smiley faces rendered with React and D3 display a reusable, component-based approach to SVG visualization. Each face uses a yellow background circle, two eyes positioned by offset coordinates, and a mouth drawn with `d3.arc()` using an inner and outer radius. The `FaceContainer` component wraps the SVG and applies a centering transform, while the `App` component renders four faces at different stroke widths to show variation. The code demonstrates how React components manage SVG elements while D3’s arc generator handles the path geometry.