This example shows a simple React application that renders a dropdown menu for choosing a pet. The code uses React 16.13.1 and ReactDOM to mount an `App` component into the DOM, displaying a labeled `<select>` element with six pet options. The interface is styled with a large font size for the message class, though that class is not applied in the current component. The rendering approach relies on `ReactDOM.render` to inject the component into the root element defined in the HTML.