Final answer:
The operating system used in Macintosh computers is macOS. macOS is a proprietary operating system developed by Apple specifically for their Macintosh computers. Hence the correct answer is option A
Step-by-step explanation:
The operating system used in Macintosh computers is macOS. macOS is a proprietary operating system developed by Apple specifically for their Macintosh computers. It is known for its user-friendly interface and seamless integration with other Apple devices and services.
Hence the correct answer is option A