A smiley face rendered with React and D3 in SVG shows a yellow circle with blue rectangular eyes and a curved mouth. The code defines an arc generator with `d3.arc` to create the mouth path, while React components manage the SVG elements. Circles for the eyes and highlights are positioned with offsets, and a group transform centers the face. The visualization demonstrates a simple, declarative composition of React state (none here) and D3 geometry primitives.