This example renders a yellow smiley face using React and D3. The face is drawn with SVG shapes, including two circles for the eyes and a D3 `arc()` generator to create the mouth path with a specified inner radius, outer radius, and angle range. The app uses React to manage the component structure, while D3’s arc function calculates the curved mouth geometry. The SVG canvas is set to 960 by 500 pixels, with the face centered and styled with a black stroke.