The CPU, after receiving an interrupt from an I/O device A. halts for a predetermined time B. hands over control of address bus and data bus to the interrupting device C. branches off to the interrupt service routine immediately D. branches off to the interrupt service routine after completion of the current instruction E. None of the above

The correct answer is: C. branches off to the interrupt service routine immediately.

When an interrupt is received, the CPU saves the current state of the processor (including the instruction pointer, program counter, and status register) and then branches to the interrupt service routine. The interrupt service routine then handles the interrupt and, when it is finished, returns to the instruction that was interrupted.

Option A is incorrect because the CPU does not halt for a predetermined time. It branches to the interrupt service routine immediately.

Option B is incorrect because the CPU does not hand over control of the address bus and data bus to the interrupting device. The CPU retains control of the address bus and data bus during the interrupt service routine.

Option D is incorrect because the CPU does not branch off to the interrupt service routine after completion of the current instruction. It branches to the interrupt service routine immediately.

Option E is incorrect because the CPU does branch off to the interrupt service routine immediately.