Operating systems provide interfaces between which components?

• A. Provides interface between human and machine
• B. Provides interface between application and the machine for other software
• C. Both A and B
• D. None of the above

Answer: (C)

Operating systems act as a communication layer that bridges people and the machine, and also bridges applications and the machine. For people, the OS provides user interfaces such as command-line shells and graphical desktops, letting users interact with the computer without handling hardware details. For software, it offers a programming interface—system calls, APIs, and libraries—that applications use to request CPU time, memory, I/O, and other services through the OS. Because it serves both roles, it covers interfaces for both human users and software, making the option that encompasses both aspects the best choice. The other options would be incomplete since they only address one side or none of these bridge roles.