A red arrow with a marker follows the mouse pointer, leaving a thin white trail behind it as the user moves across the screen. The visualization demonstrates unidirectional data flow: a `mousemove` event updates the state, which triggers a re-render of an SVG path using D3 v7. The path is drawn with a quadratic Bézier curve (`T` command) between offset coordinates, with its endpoint styled by an SVG marker definition. The code updates the `d` attribute on each render to reflect the latest cursor position.