This example demonstrates basic SVG shapes and data binding using D3.js. It appends two circles and three rectangles to an SVG container, with the rectangle heights determined by values from a hardcoded array. The code uses `d3.select` to access the SVG element and `append` functions to create visual elements. Interactive behavior is added by attaching `onclick` handlers to the rectangles via the browser's `querySelectorAll` and `setAttribute` methods.