Smiley face part I
A yellow smiley face rendered with SVG sits at the center of a 960×500 canvas, featuring black-outlined circular eyes and an arc for a mouth. The React app composes three components—BackgroundCircle, Eyes, and Mouth—each taking size and position props. D3’s `arc()` generator creates the mouth path from inner and outer radii and start/end angles, while explicit coordinates place the eyes. The face is drawn as a single group translated to the canvas center, with a yellow fill and black stroke applied to the background circle.