A cheerful cartoon face drawn with SVG animates its features using D3 transitions. The code selects an SVG element and uses D3’s `arc` generator to morph a mouth from an open grin to a filled shape over three seconds. Eyes blink by scaling their radius, while rectangular eyebrows shift vertically in sync. Built with React and D3 v5, the example leverages chained `transition().duration()` calls to create simple, looping motion between states.