Three buttons update a row of SVG circles and labels, demonstrating data joins with enter, merge, and exit selections in D3 v6. Clicking ABC renders green circles labeled A–C, DEF renders red circles D–F plus Y, and the initial view shows blue X–Z. The `selectAll('circle')` and `selectAll('text')` bind arrays of objects specifying fill color, y-position, and text, with transitions handled manually through the button click handler and a render function.