Why is the Operating System viewed as a resource allocator & control program?

A computer system has many resources - hardware & software that may be required to solve a problem, like CPU time, memory space, file-storage space, I/O devices & so on. The OS acts as a manager for these resources so it is viewed as a resource allocator.
The OS is viewed as a control program because it manages the execution of user programs to prevent errors & improper use of the computer.