Control register

Interface

Communication protocol

None of these

Stack

Scratch pad

Address register

Status register

Accumulator

Index register

Instruction decoder

Program counter

General purpose registers

Translation look aside buffer

Program counter

All of these

It cannot have subroutine call instruction

It can have subroutine call instruction, but no nested subroutine calls

Nested subroutine calls are possible, but interrupts are not

All sequences of subroutine calls and also interrupts are possible