To expand interrupt by means of daisy-chain, how many interrupt vector numbers do we need and how do we identify the source of the interrupt?

Select one:

a. One interrupt vector number for all devices, and the interrupt service procedure (or interrupt handler) will have to identify the source of the interrupt by polling data lines or PPI pins.

b. Several interrupt vector numbers needed for each interrupt source, and PPI sends the corresponding vector number to the data lines

c. One interrupt vector number for each device, and PPI sends the corresponding vector number to the data lines

d. Several interrupt vector numbers needed for each interrupt source, and identifying the source of the interrupt can be done by the interrupt service procedures by polling data lines or PPI pins