Process Control Block (PCB, also called Task Controlling Block) is a data structure in the operating system kernel containing the information needed to manage the scheduling of a particular process.
Process Control Block generally contains-
- A numeric identifier for the process i.e. pid
- A stack pointer which is required to be saved when the process is switched from one state to another to retain the current position of the process.
- Identifier of the parent id i.e. ppid
- user identifier (uid) - id of the user responsible for the process.
- CPU registers- various register set of CPU where process need to be stored for execution for running state
- A list of I/O devices allocated to the process.
- information of page table, memory limits, segment table depending on memory used by the operating system.etc.
So, Process Control Block does contain Process ID, User Identification Number, Registers.
∴ The answer will be Option D) None of the above