A yellow circle with black outlines forms a sad smiley face, its mouth rendered as an inverted arc and eyes positioned with a fixed offset. The example demonstrates basic D3.js v5 shape generation and SVG manipulation, using `d3.select` to target the SVG element and `d3.arc` to construct the downward-curved mouth path. All facial features are centered via group transformations, with dimensions derived from the SVG's width and height attributes.