This example demonstrates how D3 selections manage the lifecycle of SVG circles through enter, update, and exit phases. Randomly generated data from a custom `data` function initially renders five blue circles, which are then updated to grey with a fixed radius of 11. The code explicitly uses `d3.select('svg')`, `.selectAll('circle')`, `.data()`, `.enter()`, `.exit()`, and `.remove()` while applying chained attribute and style modifications. Although an update with ten circles exists, it remains commented out, so only the initial static rendering is visible.