This example displays a set of concentric circles centered on a fixed point, each filled with a different color and outlined in black. A small red circle is appended separately within the same SVG group. The visualization is built using D3 v5’s `select` and `append` methods to create SVG circles, with positions and radii driven by an array of JavaScript objects. The colored circles are stacked using `data.reverse()` to layer them from largest to smallest.