Which of the Following Principles Is Used to Improve the Efficiency

Multiple Choice

Which of the following principles is used to improve the efficiency of I/O?

A) Reduce the number of times that data must be copied in memory while passing between device and application.
B) Move processing primitives into hardware, to allow their operation in device controllers to be concurrent with CPU and bus operation.
C) Increase concurrency by using DMA-knowledgeable controllers or channels to offload simple data copying from the CPU. 

D) All of the above.