This example demonstrates a simple dropdown menu for selecting an option from a list, using React state to track the chosen value and update the UI accordingly. The app renders a labeled `<select>` element via a reusable `Dropdown` component, which maps an array of four options into `<option>` elements. It uses React hooks (`useState`) to manage the selected value and D3 v5 for DOM manipulation, though no visualization is drawn—the focus is purely on interactive menu controls within a React framework.