ANS:C - 13

Each IRQ has a different function or relates to a different aspect of the computer.

IRQ1 relates solely to keyboard problems. In the case of IRQ2 there can be a conflict if IRQ9 is being used at the same time. This interrupt, the IRQ2 is a cascade for IRQs 8 to 15. It enables extra IRQs 8 to 15 to be used.

IRQ 0 -- timer.
IRQ1 -- keyboard interrupt.
IRQ 2 -- cadcade interrupt.
IRQ 3 -- second serial port.
IRQ 4 -- first serial port.
IRQ 5 --- sound card.
IRQ 6 -- flopy disk.
IRQ 7 -- first parallel port.
IRQ 8 -- System.
IRQ 12 -- Mouse.
IRQ13 -- floating point unit/coprocessor.
IRQ 14 -- IDE Hard drive Primary.
IRQ 15 -- IDE Hard drive Secondary.