A green SVG smiley face is drawn using D3.js v5, with a circular head, two eyes, rectangular eyebrows, and an arc-shaped mouth. The eyebrows continuously move up and down via chained `transition()` calls with a 2000-millisecond duration. The face is centered using an SVG `<g>` element transformed by the width and height of the `<svg>` container. The code uses D3's `select` and `arc` functions to construct the shapes and animate them.