Which of the following methods are used to pass any number of parameters to…

Answer: Block in main memory and stack

Why this is correct:

• Stack — the caller pushes parameters onto the user stack before the system call; the kernel retrieves them from the stack using the stack pointer. This approach supports a variable number of parameters.

• Block in main memory — the caller constructs a contiguous block or table (for example, an array) containing all parameters and passes a pointer to that block; the kernel dereferences the pointer and reads the parameters. This method is suitable for arbitrarily many or large parameters.

Why not registers alone:

Registers are limited in number and can carry only a small, fixed number of arguments. For this reason, registers alone cannot handle arbitrary-length parameter lists.

Typical implementation:

• A hybrid approach is common: small or frequently used arguments are placed in registers for speed, and remaining arguments are passed on the stack or via a pointer to a memory block.