Programmed I$/$O$,$ interrupt$-$driven I$/$O and direct access memory $($DMA$)$ are three synchronisation methods to control data transfer between I$/$O devices and the CPU.

Which one of the following statements is TRUE for interrupt$-$driven I$/$O$?$

a$.$ The CPU keeps checking the status of the I$/$O device. When it is ready, the CPU transfer the data.

b$.$ The $\frac{1}{0}$ device informs the CPU that it is ready for data transfer.

c$.$ Large blocks of data is transferred via a controller to relieve the CPU of some functions.

d$.$ A lot of CPU time is wasted with the interrupt$-$driven method.