The correct answer is: D. DMA
DMA (Direct Memory Access) is a method of transferring data between an I/O device and memory without the intervention of the CPU. This allows for much faster I/O transfers, as the CPU is not involved in the data transfer process.
Interrupts are a way for an I/O device to notify the CPU that it needs attention. The CPU then stops what it is doing and handles the I/O request. This can cause delays in I/O transfers, as the CPU may be busy with other tasks.
Memory mapping is a way for the CPU to access memory that is used by an I/O device. This allows the CPU to read and write data to the I/O device without having to go through the I/O controller. However, memory mapping does not speed up I/O transfers.
Program-controlled I/O is a method of controlling I/O devices by the CPU. The CPU reads and writes data to the I/O device directly. This is the slowest method of I/O, as the CPU is involved in every data transfer.
In conclusion, DMA is the method which offers higher speeds of I/O transfers.