What is the primary operational purpose of an Operating System acting as a resource allocator?
Option A is correct. To manage and allocate system resources (CPU time, memory space, file storage, I/O devices) efficiently and fairly among competing programs.
Which mechanism allows the hardware to distinguish between instructions executed on behalf of the operating system and those executed by user applications?
Option B is correct. Dual-mode operation using a hardware Mode Bit (0 for Kernel mode, 1 for User mode).
Which of the following operations is classified as a privileged instruction that can ONLY be executed in Kernel mode?
Option C is correct. Disabling hardware interrupts, modifying I/O device control registers, or altering memory management timers.
How does a user-level program request a service from the Operating System kernel (such as reading a file from disk)?
Option A is correct. By issuing a System Call, which triggers a trap/software interrupt to switch CPU mode from User to Kernel mode.
In UNIX/Linux operating systems, which system call is used to create a new, duplicate child process?
Option B is correct. fork()