This force-directed network diagram displays relationships between four concepts—people, radiation, seeds, and cancer—with link opacity encoding connection strength. It is built with D3 v3’s `d3.layout.force` simulation and SVG rendering, with arrow markers on curved paths. Clicking a node enlarges its circle and changes its label color, while a double-click resets the size. The data is loaded from `data.json` via `d3.json`.