This example shows a smiling face rendered as an SVG using React components. It draws a yellow circle for the head, two black circles for the eyes, and a curved path for the mouth. The code uses React for the user interface, ReactDOM to mount the component, and the `arc` function from D3 to generate the mouth’s path. The face is centered with fixed dimensions for stroke, eye offset, and radius, demonstrating a simple composition of SVG elements built with React and D3.