Smiley Face
A classic smiley face rendered as an SVG in React, using D3’s `arc()` generator to draw the mouth as a curved path. The face consists of three `circle` elements for the head and eyes, with a yellow fill and black stroke, all centered via a translation transform. D3 v5 provides the arc geometry, while React 18 manages the component’s declarative SVG output, with hardcoded dimensions and positions defining the layout.