The correct answer is: B. Operating system
The operating system is the layer of a computer system between the hardware and the user program. It provides a platform for running programs and managing resources, such as memory, storage, and processing power.
The operating environment is the set of programs and tools that provide a user interface and other services to the operating system.
The system environment is the physical environment in which the computer system operates, including the hardware, software, and network resources.
None of the other options are correct.