A yellow smiley face rendered in SVG animates its eyebrows in a repeating up-and-down motion. Drawing from a simple hardcoded set of shape parameters, the code uses D3 selections and the `arc` generator to construct the face, eyes, mouth, and rectangular eyebrows. The animation relies on chained `transition` calls with a two-second duration to move the eyebrow group along the y-axis. The example is built with D3 v6 within a React starter project, targeting the SVG element directly.