A yellow circle becomes a cartoon face with black-outlined features, built using D3.js selections and SVG primitives. The example constructs the face from a central `circle` for the head, two smaller circles for eyes, and a `path` generated with the `arc()` generator to form a half-circle mouth. Two white rectangles serve as teeth, with the right tooth animating downward via a chained `transition().duration(2000)` that changes its `y` attribute. The code utilizes D3 v5’s `select`, `arc`, and transition APIs within a React framework, rendering to an SVG canvas.