Smiley Face Part I
A yellow smiley face rendered with React and D3 v7 uses SVG circles for the head and eyes, plus a D3 arc path for the mouth. The head circle is centered in a 960 by 500 viewport and sized relative to the height, with the eyes offset horizontally and vertically. The mouth arc is generated with `d3.arc()` using inner and outer radii and a half-circle angle range.