A simple interactive SVG circle follows the mouse pointer across a 960-by-500 blank canvas, updating its position in real time. The visualization uses React 17 with the `useState` hook to manage the circle’s coordinates, which are updated on every `mousemove` event on the SVG element. The circle’s center is set via the `cx` and `cy` attributes, while D3 v5 is loaded but not directly used in the rendering logic. The example demonstrates state-driven updates in a React-rendered SVG without any external data source.