The example demonstrates D3 selections in action by creating a full-screen SVG canvas and appending it to the document body using `d3.select`. It sets the SVG’s dimensions to match the browser window’s width and height via `window.innerWidth` and `window.innerHeight`. The code uses the `select` method from the D3 library, version 7.6.1, to chain an `append('svg')` operation and assign width and height attributes. This minimal setup serves as a foundational illustration of D3’s selection and DOM manipulation capabilities within a React framework context.