A yellow circle with eyes, eyebrows, and a mouth forms a smiling face, rendered as SVG elements. The right eyebrow animates upward and back down over four seconds using D3 transitions. The face is centered in a 960×500 viewport, with the mouth drawn via the `arc` generator and all shapes grouped and translated using D3's `select` and `append` methods. The animation runs in an infinite loop, triggered by chained `transition().duration()` calls on the eyebrow rectangle.