I need help with this question. (Operating system)

(8%) Memory access and I/O Operations. Interrupt-driven I/O, programmed L/O, and DMA 10. Consider the following techniques for IC) operations: a) (2%) Which technique may compete with the CPU for bus access? b) (2%) Which technique requires the CPU to periodically check the IO status? c) (4%) what information must be sent to the DMA module if the processor wishes to read or write data