Which program handles a printer's driver automatically in macOS?

The program that automatically handles a printer's driver in macOS is AirPrint. AirPrint is a technology developed by Apple that allows users to print over a wireless network without the need for additional drivers or software. When you connect an AirPrint-enabled printer to the same network as your Mac, the Mac can automatically discover the printer and communicate with it seamlessly, thus simplifying the printing process.

By using AirPrint, users can easily print documents, photos, and web pages directly from their macOS applications without needing to worry about finding and installing specific printer drivers. This feature enhances convenience and saves time, as it streamlines the setup and usage of printers in the macOS environment.

The other options serve different functions: Bonjour is a network discovery service that helps devices find each other on the network, the Magic Mouse refers to a specific Apple accessory designed for navigation, and iCloud is Apple's cloud storage service, which is not directly related to printer management or drivers.