Concept:An Operating System acts as an intermediary between the user and computer hardware, managing all major resources and processes.
Explanation:An Operating System controls system resources and ensures they are shared properly among running programs.
It manages the main memory by allocating and freeing space for processes.
It handles file storage, including creating, reading, writing, and organizing files on storage devices.
It also supervises the execution of applications, coordinating tasks such as starting, running, and closing programs.
Since these duties include memory, file, and application management, the OS performs all the listed functions.
Answer:D. All of the above