This example shows a smiley face rendered as an SVG using React components for each shape, with D3 generating the mouth path. The face consists of a yellow circle with a black stroke, two eye circles, and an arc created by `d3.arc()`. React manages the SVG elements declaratively, while D3 provides the arc generator with specified inner and outer radii and start/end angles. The code uses React 16 and D3 v5, rendering directly into the DOM via `ReactDOM.render` with static positioning based on fixed dimensions.