A React and D3 v7 composition builds a smiling face, showing how reusable SVG components combine through props. The `Face`, `Eyes`, `Mouth`, and `Teeth` components use D3's `arc()` generator to create concentric shapes, while a `linearGradient` fills the background circle in green-to-yellow. A static set of line elements renders teeth, with prop-driven dimensions controlling eye radius, mouth width, and offsets.