A yellow circle becomes a smiley face as the animation runs. D3 v5 builds the face from SVG shapes—a circle for the head, two circles for eyes, two rectangles for eyebrows, and an arc path for the mouth—centered within an SVG canvas. The left eyebrow briefly moves upward via chained `transition` calls, while all other elements remain static. The code uses d3-selection, d3-arc, and SVG attributes, with no external data source.