Correct option is A
Isolated I/O and Memory-Mapped I/O are methods for addressing I/O devices. In Isolated I/O, memory and I/O addresses are distinct, allowing the CPU to differentiate between memory and I/O operations. This method uses separate address spaces, making it easier for the CPU to manage I/O.
Memory-Mapped I/O, however, shares the same address space for both memory and I/O devices, allowing I/O devices to be addressed as if they were memory locations. Both methods have their own advantages and are chosen based on system design requirements.