Which of the following statements about interrupt is/are true?

a. The interrupt frees the CPU from checking I/O requests from a loop;

b. When the CPU is processing a loop, it has to jump out of the loop immediately as it receives an interrupt request;

c. mfc0 instruction is executed if the CPU wants to check the reason of the interrupt;

d. When the keyboard interrupts the CPU, the CPU invokes ISR stored in keyboard to handle it;

e. None of the above.