This example demonstrates a minimal starting point for a D3 visualization, rendering a simple red circle with a radius of 100 units onto an SVG canvas. The code imports the `select` function from the D3 library (version 7) and uses it to select the SVG element and append the circle with specified attributes. The HTML file loads D3 from the unpkg CDN and includes a body styled with massive 13em font size, while the JavaScript logic resides in a separate `bundle.js` file.