A smiling face made of SVG shapes animates its eyebrows in a looping motion. The example builds the face by centering a yellow circle, adding two eyes, and drawing a mouth using the `arc` generator from D3.js v5. Eyebrow rectangles are grouped and moved using `transition` and `attr` with a 2-second duration, shifting vertically up and down. The code imports `select` and `arc` directly from the `d3` module, sets attributes like `r`, `cx`, and `x` for positioning, and uses a 960×500 SVG canvas with a transform to center the composition.